Colder Thermostat

[syncrotrev]

so your tuner never stressed the importance of having vcds or required to see logs? IMO, that's somewhat irresponsible, and gives a false sense of security. i wouldn't tune anyone unless they at least have vcds-lite but that's just me. at least you have good gauges and a scanner so presumably you can at least watch live data (right?) and aren't completely blind... but if i were to give someone a tune who doesn't have vcds (but good gauges) - i would stress the importance of having it (as in, it's basically mandatory) and only give it with a huge disclaimer lol. there's simply too much that can go wrong, and can BE wrong without one even realizing it, or at least to a degree it may seem like not a big deal when it could be... and if the tune that was given (which should of course be near perfect for the hardware) doesn't perform as expected by butt dyno/any gauge readings, without being able to log basic data, you're going to be very handicapped as to being able to figure out what it is. maybe the tune isn't quite right? maybe there's a mistake in the tune. maybe there's some small or even serious hardware issue that you weren't aware of.

I FULLY agree with you. I will get it and likely DM you for some pointers! Thanks!

 

[syncrotrev]

I'm still wanting to know why you think it is actually running hot.

My T3 experience has always been that it takes a lot of driving to get the ENTIRE cooling system warmed up. You already said the radiator feels cool.

What's the oil temp like? That's typically what VAG uses as a metric for "full operating temp", not coolant temp.

As I said, 213F is not "hot", and it would also be useful to know specifically where that value is being taken. You also may find that, as is the nature of non-throttled diesels, they build heat when under load, and cool back down when they return to idle or low load operation.

If you see a value at the CTS data (so, on the cylinder head outlet... the "hottest" part of the engine) of 100C, and the thermostat has an opening rating of 87C stamped right on it, then assuming it is in fact open and the coolant is in fact flowing, there should be a heat transfer starting at the big coolant tube coming from the engine to the front to the radiator.

Does your van still have its rear heater core in place? Is it hot if the manual valve is open? Does the front core get hot if moved to warm? That's at least tell you there is some coolant flowing.

While it is no TDI, and it isn't even a camper let alone loaded down, my [factory] diesel Vanagon could probably be driven down the road for an hour on a cool (not cold) day and the coolant going through the heater cores is enough to maintain engine cooling. The thermostat likely never opens, LOL.

Also, make certain the coolant pipes to the radiator are in the correct orientation in the rear. If memory serves, the "hot" tube goes to the top of the radiator. Since the 2.1L era vans like yours do not use the steel pipes like the 1.9L did, you could easily swap those two tubes. Not sure it would really change anything, though. But it might. Because cooler coolant would want to go to the bottom of the radiator, so maybe if they were switched???

Hey oil hammer, I agree with you, that the temps are fine. My original post was due to what I was seeing on other threads about op temps. So I doo feel better. Thank you.

To answer some of your questions. I will check my hose layout when I get home. But I’m pretty sure everything is dialed. I went through an extensive cooling system rebuild with andybees a while back. I do have the factory rear and front heater cores and they work very well. Almost too well to be honest. Up to temp in 5-15min and very hot. My wife and kids feel like the air is burning them they say. Haha.

it honestly feels like the heat is just staying around the motor, not moving to the rad way up front. But again both heater cores work. If I hit 215°F on my scan gauge I do get some leaking from some fittings and a little boil over out of my expansion tank.

I’m going to check the hoses like you say, and I have a new thermo on the way. Hope something there helps.

thanks as always.

 

[syncrotrev]

I'm still wanting to know why you think it is actually running hot.

My T3 experience has always been that it takes a lot of driving to get the ENTIRE cooling system warmed up. You already said the radiator feels cool.

What's the oil temp like? That's typically what VAG uses as a metric for "full operating temp", not coolant temp.

As I said, 213F is not "hot", and it would also be useful to know specifically where that value is being taken. You also may find that, as is the nature of non-throttled diesels, they build heat when under load, and cool back down when they return to idle or low load operation.

If you see a value at the CTS data (so, on the cylinder head outlet... the "hottest" part of the engine) of 100C, and the thermostat has an opening rating of 87C stamped right on it, then assuming it is in fact open and the coolant is in fact flowing, there should be a heat transfer starting at the big coolant tube coming from the engine to the front to the radiator.

Does your van still have its rear heater core in place? Is it hot if the manual valve is open? Does the front core get hot if moved to warm? That's at least tell you there is some coolant flowing.

While it is no TDI, and it isn't even a camper let alone loaded down, my [factory] diesel Vanagon could probably be driven down the road for an hour on a cool (not cold) day and the coolant going through the heater cores is enough to maintain engine cooling. The thermostat likely never opens, LOL.

Also, make certain the coolant pipes to the radiator are in the correct orientation in the rear. If memory serves, the "hot" tube goes to the top of the radiator. Since the 2.1L era vans like yours do not use the steel pipes like the 1.9L did, you could easily swap those two tubes. Not sure it would really change anything, though. But it might. Because cooler coolant would want to go to the bottom of the radiator, so maybe if they were switched???

Oh also my oil temps are around 180-200. Maybe 230 after a long pull up a pass. But the cool back down quickly. Running a dual filter system with an external Baja bug style cooler up front. So lots of extra oil capacity.

 

[burpod]

those temps do sound fine, the only concern i would have is coolant running a bit hot being an indicator that things aren't running as optimally as they should. the temp of the coolant itself, isn't anything i would be directly worried about. it's what it means is what bothers me like, if it were my van, i'd be hoping to see lower coolant temps.... i wouldn't want to see >200F

 

[oilhammer]

I would. And I'd want to see the oil temp at least get up over 212F, so it is for certain to completely boil away any water vapor in the crankcase to be scavenged away. There is absolutely such a thing as "too cool" of engine operating temp. It isn't good for fuel economy, it certainly isn't good for emissions, and it isn't really good for the engine.

Diesels don't have it quite as bad, as they normally run lean anyway. But still, extended idling and "wet stacking" is a thing. Why do you think covering the engine radiator grill in winter is a thing? Because they often just run TOO cool. Prechamber diesels had a hot soak high load problem. Direct injected ones don't. They carry much of the heat away in the exhaust, because it stays concentrated in the bowl of the piston.

But in the case of the T3, they have a LOT of coolant. The ALH cars hold about 6 liters of coolant. The T3 (at least with the 2.1L waterboxer) hold a whopping SIXTEEN liters of coolant. That's why they are the only water cooled Volkswagens to get both the expansion tank AND the overflow tank. Because the amount (volume) of expansion from cold to hot is significantly more when you hold over twice as much. That's also why they have so many air bleed spots.

I would defer to Andy on his knowledge of ALHs in T3s, however his was born a 1.9L, not a 2.1L, and their cooling systems are a little different.

When temps (oil and/or coolant) go up and keep going up, or do not stabilize or come back down when the conditions change, THEN you may have a heat saturation problem. I don't think in this instance you really do. And the heat working as well as it does (again, these use valves, not constant-flow heater cores like the FWD stuff) leads me to think the cooling system is doing its job, and the thermostat probably never even needs to open all the way except for some short specific high load events. Does the radiator fan ever even come on? I'd check the temps with a heat gun to see if it is EVER even getting enough heat at the thermoswitch to turn the fan on. You always know when those fans come on, they move some air (single 450w motor, right inches from your right foot!).

 

[syncrotrev]

I would. And I'd want to see the oil temp at least get up over 212F, so it is for certain to completely boil away any water vapor in the crankcase to be scavenged away. There is absolutely such a thing as "too cool" of engine operating temp. It isn't good for fuel economy, it certainly isn't good for emissions, and it isn't really good for the engine.

Diesels don't have it quite as bad, as they normally run lean anyway. But still, extended idling and "wet stacking" is a thing. Why do you think covering the engine radiator grill in winter is a thing? Because they often just run TOO cool. Prechamber diesels had a hot soak high load problem. Direct injected ones don't. They carry much of the heat away in the exhaust, because it stays concentrated in the bowl of the piston.

But in the case of the T3, they have a LOT of coolant. The ALH cars hold about 6 liters of coolant. The T3 (at least with the 2.1L waterboxer) hold a whopping SIXTEEN liters of coolant. That's why they are the only water cooled Volkswagens to get both the expansion tank AND the overflow tank. Because the amount (volume) of expansion from cold to hot is significantly more when you hold over twice as much. That's also why they have so many air bleed spots.

I would defer to Andy on his knowledge of ALHs in T3s, however his was born a 1.9L, not a 2.1L, and their cooling systems are a little different.

When temps (oil and/or coolant) go up and keep going up, or do not stabilize or come back down when the conditions change, THEN you may have a heat saturation problem. I don't think in this instance you really do. And the heat working as well as it does (again, these use valves, not constant-flow heater cores like the FWD stuff) leads me to think the cooling system is doing its job, and the thermostat probably never even needs to open all the way except for some short specific high load events. Does the radiator fan ever even come on? I'd check the temps with a heat gun to see if it is EVER even getting enough heat at the thermoswitch to turn the fan on. You always know when those fans come on, they move some air (single 450w motor, right inches from your right foot!).

So temps always stabilize. If I’m pulling a long steep pass, they will climb in the first few miles. Then lock in at say 215°F then as I crest the top they cool down in a few miles as well. If I’m climbing the pass and I need to down shift for power or to lower EGT’s, and I spin the motor up to 3300-3500rpm then the temps just drop almost instantly to sub 200 in under 1 min.

I did use a laser heat gun, and never got hot enough temps around my switch to turn the fans on. (Bran new switch by the way) then for kicks I put the fans on a switch and ran the temps up on a hill and manually turning on the fan does nothing to drop temps. But if I turn the heaters on I can dump 10°F right away.

I’ll check in with Andy. That dude does know his TDI conversations. For the record I think we have the same ALH. A 1.9.

 

[oilhammer]

Yes, you both have the same ALH now. But his van is an earlier waterboxer, 83.5-85, that used the 87hp 1.9L Digijet waterboxer (and those were ALL 2WD only). Yours was a 95hp 2.1L Digifant waterboxer, which had the AWD optional, '86-91. The cooling systems of those two era/engines are completely different. They share no parts except maybe the radiator itself. But the entire plumbing system is completely different. So what he did on his van may or may not apply to yours, that's all I was saying.

I wonder if his van's radiator ever gets warm enough to trigger the cooling fan. I always felt like you lose a fair amount of heat just on the way forward to the radiator... you have a tube larger than a garden hose that has air passing around it underneath.

May also just have a less-than-ideal radiator internals, but I cannot say I've ever seen a Vanagon with a clogged up one, and I've seen more neglected and butchered and beat on waterboxer Vanagons in my life than most people ever would.

 

[syncrotrev]

Yes, you both have the same ALH now. But his van is an earlier waterboxer, 83.5-85, that used the 87hp 1.9L Digijet waterboxer (and those were ALL 2WD only). Yours was a 95hp 2.1L Digifant waterboxer, which had the AWD optional, '86-91. The cooling systems of those two era/engines are completely different. They share no parts except maybe the radiator itself. But the entire plumbing system is completely different. So what he did on his van may or may not apply to yours, that's all I was saying.

I wonder if his van's radiator ever gets warm enough to trigger the cooling fan. I always felt like you lose a fair amount of heat just on the way forward to the radiator... you have a tube larger than a garden hose that has air passing around it underneath.

May also just have a less-than-ideal radiator internals, but I cannot say I've ever seen a Vanagon with a clogged up one, and I've seen more neglected and butchered and beat on waterboxer Vanagons in my life than most people ever would.

Copy that. Here is my system after I talked with Andy. My main rad lines are all upgraded hard pipe like you mention above.

 

[oilhammer]

So your charge air cooling has its own, independent cooling supply? Looks like it does.

When the engine has been driven, and it has gotten as warm as it is going to get (and I realize it will cool back down quickly), if you take the bleed screw out the top of the radiator with the engine still running, does HOT coolant with no bubbles come out?

Are you not running the extra overflow tank bottle?

What are the little 'X' markings at the terminus of those three red small hoses in your diagram?

Is your engine at the normal 15 degrees? Or laid over at 40?

 

[syncrotrev]

So your charge air cooling has its own, independent cooling supply? Looks like it does.

When the engine has been driven, and it has gotten as warm as it is going to get (and I realize it will cool back down quickly), if you take the bleed screw out the top of the radiator with the engine still running, does HOT coolant with no bubbles come out?

Are you not running the extra overflow tank bottle?

What are the little 'X' markings at the terminus of those three red small hoses in your diagram?

Is your engine at the normal 15 degrees? Or laid over at 40?

Yes the air cooling is on a separate circuit closed to the rest of the cooling system.

I will try the screw and see what happens.

I am not running the extra tank. I do understand that a lot of these do because of the shear volume of coolant. You think I should add one? if so should I add the aluminum ones gowesty sells, or just a 2nd ball like stock. Also if I do add it, where would it be installed to work properly? Lastly would just a larger overflow tank accomplish the same goal?

The x markings are small hoses that are plugged. They go nowhere. They were done by the company that did the conversion. They are since not doing conversions or consulting on the ones they did. So on my own here.

Motor is at 15º. I know some are at 50º. Mine is 15º

 

[oilhammer]

Looks like the plugged ones were for the engine oil cooler and a transmission cooler, if they are both on the pipe that wraps around the engine. They heater-hose sized lines?

15 is good, that way the steam vent from the EGR cooler as well as the head itself should be working fine (the purple lines in your diagram).

Regarding the extra tank.... are you familiar with the stock 2.1L waterboxer (or ANY water cooled Vanagon, for that matter) plumbing and how the overflow tank is arranged?

 

[syncrotrev]

Looks like the plugged ones were for the engine oil cooler and a transmission cooler, if they are both on the pipe that wraps around the engine. They heater-hose sized lines?

15 is good, that way the steam vent from the EGR cooler as well as the head itself should be working fine (the purple lines in your diagram).

Regarding the extra tank.... are you familiar with the stock 2.1L waterboxer (or ANY water cooled Vanagon, for that matter) plumbing and how the overflow tank is arranged?

Yes, they are heater sized lines. And that makes sense.

All my vanagons have had Subaru's or TDI's so I am sadly unfamiliar with the stock set ups. I know bit's and pieces about them as I'm around them and such. I can look in my Bentley and see what it has, but I doubt it has a cooling diagram. Anything in particular that would be helpful to me that's on your mind?

 

[oilhammer]

So I'll explain it as best I can.

As mentioned above, the T3's cooling system capacity is enormous. Not because of some extra need to cool things, although the fact that these are technically commercial trucks in a sense does call for that... but the real reason is just the distance the radiator is from the engine. They hold as much coolant as many big V8 engines do. Heck, the big 4.9L I6 in my F150 holds less coolant.

So, Volkswagen added the extra, non-pressurized overflow bottle. It would have lived right inside the engine bay, and its level and fill cap can be viewed and accessed from the drop down flap where the license plate goes. The bottle they used, which is the expansion tank, was mounted right next to it, and was the same oval-shaped arrangement common to other VAG products of the era, like what an A2 Golf or Jetta or B2 Quantum or something would have used. BUT... the cap was a special T3-only setup, with a little nipple made on to it, and a hose that went over to that extra tank.
In essence, they piggybacked two types of cooling systems into one. The modern, pressurized, setup with the expansion tank just like every other Volkswagen in the modern era uses, but also the old-fashioned vent/recovery tank like some older cars as well as some newer cars still use today. The volume in the expansion tank doesn't allow enough room (the area above the centerline... sometimes marked MIN-MAX) just isn't large enough to accommodate the amount of expansion necessary for that amount of coolant.

The newer tanks that an ALH car would use do not allow for that type of cap to be installed. So you've got to deal with some way to try and alleviate this discrepancy if at all possible.

1983-1991 VW Vanagon Cap For Expansion Tank - BLAU Germany - 025121321-BL (jbugs.com)

If you are still using the old style tank, that allows the use of the small cap, then all you need to do is plumb in some overflow tank somewhere, that maybe can hold a couple liters of liquid. Bad side of doing it like that, though, is that HOAT coolants (like G12) do not like that exposure to atmosphere (T3s all left the factory with the blue G11 type coolant, which isn't as bad about the additives dropping out of suspension like G12 is).

So another thing could be to simply use TWO modern type tanks. That would double the expansion potential... which would help, but it still wouldn't allow for that nearly thrice the amount of coolant capacity you are dealing with. But would certainly get you closer.

And yes, GoWesty has that nice aluminum tank that would not only help but also uses a more old-school conventional "parts store" type cap, with the nipple to the overflow tank made on to the pressure tank (like you'd normally see) instead of the hastily modified and failure prone cap that Volkswagen put on them from the factory.

 

[syncrotrev]

So I'll explain it as best I can.

As mentioned above, the T3's cooling system capacity is enormous. Not because of some extra need to cool things, although the fact that these are technically commercial trucks in a sense does call for that... but the real reason is just the distance the radiator is from the engine. They hold as much coolant as many big V8 engines do. Heck, the big 4.9L I6 in my F150 holds less coolant.

So, Volkswagen added the extra, non-pressurized overflow bottle. It would have lived right inside the engine bay, and its level and fill cap can be viewed and accessed from the drop down flap where the license plate goes. The bottle they used, which is the expansion tank, was mounted right next to it, and was the same oval-shaped arrangement common to other VAG products of the era, like what an A2 Golf or Jetta or B2 Quantum or something would have used. BUT... the cap was a special T3-only setup, with a little nipple made on to it, and a hose that went over to that extra tank.
In essence, they piggybacked two types of cooling systems into one. The modern, pressurized, setup with the expansion tank just like every other Volkswagen in the modern era uses, but also the old-fashioned vent/recovery tank like some older cars as well as some newer cars still use today. The volume in the expansion tank doesn't allow enough room (the area above the centerline... sometimes marked MIN-MAX) just isn't large enough to accommodate the amount of expansion necessary for that amount of coolant.

The newer tanks that an ALH car would use do not allow for that type of cap to be installed. So you've got to deal with some way to try and alleviate this discrepancy if at all possible.

1983-1991 VW Vanagon Cap For Expansion Tank - BLAU Germany - 025121321-BL (jbugs.com)

If you are still using the old style tank, that allows the use of the small cap, then all you need to do is plumb in some overflow tank somewhere, that maybe can hold a couple liters of liquid. Bad side of doing it like that, though, is that HOAT coolants (like G12) do not like that exposure to atmosphere (T3s all left the factory with the blue G11 type coolant, which isn't as bad about the additives dropping out of suspension like G12 is).

So another thing could be to simply use TWO modern type tanks. That would double the expansion potential... which would help, but it still wouldn't allow for that nearly thrice the amount of coolant capacity you are dealing with. But would certainly get you closer.

And yes, GoWesty has that nice aluminum tank that would not only help but also uses a more old-school conventional "parts store" type cap, with the nipple to the overflow tank made on to the pressure tank (like you'd normally see) instead of the hastily modified and failure prone cap that Volkswagen put on them from the factory.

Ok, this makes a ton of sense. Everything runs great on the car when the temps hit 215ºF. But when I get that high I see a little dribble of coolant below my expansion ball. So I am guessing that it is filling past capacity and then using that over flow vent on the side to dump what it can't hold. If I had more capacity it would not be an issue. I do have 2 of the modern ball types. If I were to add another to my system would I just branch off all the connections of the first ball tank with a T and run those lines to the 2nd ball? Essentially they would then fill at the same rate, not one fill full then the other start filling?

Also I just went for a drive and got my temps up to about 200ºF and cracked the screw on top of the rad. No liquid came out. Just air... I bled it for about 5 min until it got super slow and then closed it. Maybe I have some bubbles that are also causing some cavitation or flow issues? I'm going to get it up to temp a few more times and bled it until I get all that air out. This could be my issue all along. I read that the TDI ALH system automatically purges the air as the system runs. But that was in the original set up, not a vanagon. So maybe I need to do a better job getting the air out.

Thanks as always for your time and help!

 

[syncrotrev]

So I'll explain it as best I can.

As mentioned above, the T3's cooling system capacity is enormous. Not because of some extra need to cool things, although the fact that these are technically commercial trucks in a sense does call for that... but the real reason is just the distance the radiator is from the engine. They hold as much coolant as many big V8 engines do. Heck, the big 4.9L I6 in my F150 holds less coolant.

So, Volkswagen added the extra, non-pressurized overflow bottle. It would have lived right inside the engine bay, and its level and fill cap can be viewed and accessed from the drop down flap where the license plate goes. The bottle they used, which is the expansion tank, was mounted right next to it, and was the same oval-shaped arrangement common to other VAG products of the era, like what an A2 Golf or Jetta or B2 Quantum or something would have used. BUT... the cap was a special T3-only setup, with a little nipple made on to it, and a hose that went over to that extra tank.
In essence, they piggybacked two types of cooling systems into one. The modern, pressurized, setup with the expansion tank just like every other Volkswagen in the modern era uses, but also the old-fashioned vent/recovery tank like some older cars as well as some newer cars still use today. The volume in the expansion tank doesn't allow enough room (the area above the centerline... sometimes marked MIN-MAX) just isn't large enough to accommodate the amount of expansion necessary for that amount of coolant.

The newer tanks that an ALH car would use do not allow for that type of cap to be installed. So you've got to deal with some way to try and alleviate this discrepancy if at all possible.

1983-1991 VW Vanagon Cap For Expansion Tank - BLAU Germany - 025121321-BL (jbugs.com)

If you are still using the old style tank, that allows the use of the small cap, then all you need to do is plumb in some overflow tank somewhere, that maybe can hold a couple liters of liquid. Bad side of doing it like that, though, is that HOAT coolants (like G12) do not like that exposure to atmosphere (T3s all left the factory with the blue G11 type coolant, which isn't as bad about the additives dropping out of suspension like G12 is).

So another thing could be to simply use TWO modern type tanks. That would double the expansion potential... which would help, but it still wouldn't allow for that nearly thrice the amount of coolant capacity you are dealing with. But would certainly get you closer.

And yes, GoWesty has that nice aluminum tank that would not only help but also uses a more old-school conventional "parts store" type cap, with the nipple to the overflow tank made on to the pressure tank (like you'd normally see) instead of the hastily modified and failure prone cap that Volkswagen put on them from the factory.

Also I believe I have one of those caps somewhere... I'll see if I can find it.

 

[oilhammer]

Yeah, sounds to me like you for sure have an air pocket. Question is, was it just not bled well enough initially, or is there a condition where coolant is being pushed out from expansion and not being replaced, and an air pocket forms again (and again, and again).

But it sounds like we're on the same page, and the right track to deal with the issue. I know for sure air coming out that bleed port on the radiator is not right. But now that you've bled it, make sure the system is full again, do your drive again, and check it again.