Colder Thermostat

[syncrotrev]

Hey everyone,

So Have a TDI ALH swap in a VW Van. The van is very lifted, High top (lots of wind load) and weighs around 6000lbs. Given those things it always runs a little hot. 204ºF - 213ºF.

I see guys on here talking about running 160ºF, 170ºF, and 188ºF thermostats. Mine is the 87ºC or 188ºF one and I am wondering if running a colder one would help me get my normal temps around 195ºF - 200ºF.

From what I am reading 195ºF - 200ºF is ideal. I know everyone on here is likely having issues the other direction... trying to get more heat. But I think with my situation I need colder.

Looking to source a thermo somewhere. Anything colder than 87ºC. I can't seem to find them anywhere.

Thanks for the help.

-T

 

[jmodge]

That temp isn’t too bad. Thermostat change may or may not help you any.
The radiator cools the coolant as it sits in the radiator while the thermostat is closed. Maybe you need to make that system more efficient.
Maybe even venting the engine bay, like a boat. Not sure what options you’ll find for stats, I run 195’s.
I’d suggest just start going through autopart suppliers websites. See what options they offer. Grab a few and test them on the stovetop for opening and closing temps.

 

[syncrotrev]

That temp isn’t too bad. Thermostat change may or may not help you any.
The radiator cools the coolant as it sits in the radiator while the thermostat is closed. Maybe you need to make that system more efficient.
Maybe even venting the engine bay, like a boat. Not sure what options you’ll find for stats, I run 195’s.
I’d suggest just start going through autopart suppliers websites. See what options they offer. Grab a few and test them on the stovetop for opening and closing temps.

Thanks, the engine bay is super open in these vans compared to a stock Jetta or golf. Not sure if that is helping or not.

One thing is that the RAD is like 8’ away from the motor. Way up front. So maybe the 8’ of hose is doing the RAD’s job?

That’s interesting to hear that you think those temps aren’t bad. My main concern is we will be in Central America and Mexico this summer. It’s going to be hot and I want to be prepared.

 

[03Golfer]

A cooler thermostat may offer you more headroom on a marginally sized (too small) cooling system. But the better way is to increase the cooling efficiency/capacity. Larger fans, larger rad, increased airflow, and keep the higher temp thermostat. What setup did the factory busses run?

 

[jmodge]

8 feet? Maybe you could put some heat exchangers or something on those pipes to dissipate heat. Does your heater core circulate all the time or is there a coolant shutoff valve like Toyota’s

 

[borninabus]

what's the status of the rest of your van's cooling system?

 

[syncrotrev]

A cooler thermostat may offer you more headroom on a marginally sized (too small) cooling system. But the better way is to increase the cooling efficiency/capacity. Larger fans, larger rad, increased airflow, and keep the higher temp thermostat. What setup did the factory busses run?

My "stock" van RAD is about the same size of the original "Jetta" RAD. The fan is likely undersized compared. But the cooling system is larger n general. Space is maxed. Not sure there is much room to grow. But I do agree with you.

 

[syncrotrev]

8 feet? Maybe you could put some heat exchangers or something on those pipes to dissipate heat. Does your heater core circulate all the time or is there a coolant shutoff valve like Toyota’s

Yes 8 feet. Hard piped from the rear mounted motor to the front of the car where the RAD is located. I have 2 heater cores that work very well and when I turn both on I loose anywhere from 5-10º maybe more. I also have a separate oil cooler. Ideally I would like it to just get water flow to the main RAD and with my current 87ºC thermo I want to see temps around 200ºF... I have rebuilt the entire cooling system and checked everything. Honestly it runs great. But seeing what people are claiming for normal op temps I wanted to see if I could get closer to those. However, my rig is far different.

 

[syncrotrev]

what's the status of the rest of your van's cooling system?

Oh man, I had a few forums going on that initial problem and I updated some... But I just looked and I never updated TDICLUB. I will. I was chasing that gremlin for quite some time. Getting blown head gasket systems.... but it wasn't... They I found the issue. I was running stock head bolts with injectors, big turbo, and a tune. It was too much and lifting the head under load. I have since installed ARP head studs and it has 100% fixed the problem.

 

[syncrotrev]

Does anyone know where I can find a cooler thermo to buy? It's so easy to try. I took an old thermo and drilled 2 1/16" holes in it and the better flow dropped my temps drastically. If I can get one to just open up more I think I can get the same effect. But also allow the water to warm at start up as well.

 

[GlowBugTDI]

Sounds like the thermostat you have isn't opening Fully when it's supposed to. Is it name brand? I would maybe try getting a normal or slightly lower temp one and see if it gets better. I bought 2 different (ac delco, and motorad) brand new 95 degree thermostats and both would keep my bug between 207-220 just cruising down the highway. I'd sit and idle at 200-205 at lights or in the driveway. Switched to a mahl thermo from ID parts and it has been perfect temps since.
At minimum throw it in some water on the stove and see at what temps it's popping all the way open.

you can buy low temp ones on ebay, but they are kinda junky anyway. Buy a 180 degree on there and drill holes in it if you wanna cheap out.

 

[jmodge]

That’s why I mentioned checking them on the stovetop in water. Some may start opening sooner than others, fully opened at rated temp. Some will start closing earlier than others

 

[GlowBugTDI]

That’s why I mentioned checking them on the stovetop in water. Some may start opening sooner than others, fully opened at rated temp. Some will start closing earlier than others

Agreed. In addition while this isn't caused by the tune I'd be curious to know how big of turbo, injectors and what tune. Unless that turbo is huge and there is a lot of fuel, I'd be curious about that tune. You can go pretty far before causing headlift with a decent tune.

 

[J_dude]

Agreed. In addition while this isn't caused by the tune I'd be curious to know how big of turbo, injectors and what tune. Unless that turbo is huge and there is a lot of fuel, I'd be curious about that tune. You can go pretty far before causing headlift with a decent tune.

Heh, guessing everybody with a @burpod tune is thinking the same thing here lol. Must be some significant timing advance in there eh? Tune may be contributing the temp issue as well.

 

[GlowBugTDI]

Heh, guessing everybody with a @burpod tune is thinking the same thing here lol. Must be some significant timing advance in there eh? Tune may be contributing the temp issue as well.

Well, I may be slightly bias to burpod, but yes something along the lines of tune related head lift. I have seen a few common things on high stage tunes since he red pilled me a bit. Head lift, cracked pistons, blow by, and blown turbo's. I'm not as much anti bad tuner, but I also don't have to deal with the crap that he deals with on a daily basis. Real story, I met a guy who had his ALH head blow of it's block and dent his hood. Broke studs and pulled threads from the block. He had a Facebook tune pushing all the boost and advance. I haven't seen or heard of that happening before, but I didn't see any reason for the guy to lie to me. Was an interesting story to say the least, so if he made it up he spent a decent deal of time trying to come up with a good story that nobody except someone on here would be interested in lol.

 

[burpod]

Well, I may be slightly bias to burpod, but yes something along the lines of tune related head lift. I have seen a few common things on high stage tunes since he red pilled me a bit. Head lift, cracked pistons, blow by, and blown turbo's. I'm not as much anti bad tuner, but I also don't have to deal with the crap that he deals with on a daily basis. Real story, I met a guy who had his ALH head blow of it's block and dent his hood. Broke studs and pulled threads from the block. He had a Facebook tune pushing all the boost and advance. I haven't seen or heard of that happening before, but I didn't see any reason for the guy to lie to me. Was an interesting story to say the least, so if he made it up he spent a decent deal of time trying to come up with a good story that nobody except someone on here would be interested in lol.

i actually had a guy come by yesterday with a ecu to immobo delete.. came from a "parts car" he bought, but now is deciding to fix it up - blown head gasket, engine bay an oily unkept mess - typical scumbag car with a well-known and much-touted tuner on FB on it (running way too much advance, 10mm .230s vnt17 - nothing that should come close to blowing headgaskets etc of course it had some super fancy wheels on it which weren't sold with the car lol). it's sad how many cars like this i've come across, it's pretty much non-stop with people i meet. and yeah... running real hot can be definitely a sign of too much advance.... *sigh*

 

[burpod]

That said I wouldn't jump to a any conclusions based on coolant temp, but it's something to be aware of. Logging data and understanding how things are running would go a long way

 

[oilhammer]

213F is not that hot.

The reason cooling systems are pressurized is so they can run HOTTER than the BOILING POINT of water. Which, is 212F at sea level. Most modern cars run closer to 220-230F. Now if it spikes way up, and won't come back down, you may have an issue.

You may also want to check the temps of the cooling system at various places with an infrared gun, as that might point out some poor circulation in some areas.

The late T3's radiator fan control switch low threshold is 95C, and the high speed is 102C (so about 203F and 215F, respectively). So the fans are not even supposed to come on until the radiator... all the way at the opposite end from the engine... is over 200F, which means the engine is almost certainly going to be hotter.

As a test, you could jump (force) the fan to come on low and see if your coolant temp drops. If it does, then you already know the coolant is flowing which means the thermostat is already open, and putting a "colder" one in isn't going to do anything.

 

[oldpoopie]

as others have mentioned I’d focus on making your cooling system more efficient rather than a lower temp thermostat.

 

[burpod]

i also don't think a lower t-stat would do much at all, like OH said, it's simply going to open sooner but by the sounds of it, it's probably opened up all the way so it wouldn't make any difference.

what i would do, is re-examine your cooling system to see if it has any flaws, and take logs and see if perhaps things aren't running as efficiently as they could, or if there are other noticeable things wrong (which can be difficult). but in a vehicle like that, unless some real effort has been put into making the tune the best it can be.. i'd say there probably is a large amount of room for improvement there. not just for fuel/timing/boost being optimal for your bits, but also for your gearing/load in such a beast. even just things like logging timing data to see how spec/actual timing is tracking - it's usually not an issue, but unless you actually look for it, there can be problems you don't actually notice and then attribute to other things....

so basically, other than a general re-examination, i wouldn't go about scheming some whole new design and tearing things apart before putting some effort into figuring out if the tune/hardware is really working right for you.

 

[syncrotrev]

Thanks everyone, I agree with your comments. To be honest I am not super privy to running logs and understanding things on that level. Someday I'll get VCDS and dive into all that. I agree that, that's the best route forward.

Good to know about the Temps Oilhammer. I have checked areas of my cooling system and the Rad is cold all the time. I need to check more and see where things go from hot to cold. I think I'll start with a new top shelf thermo and see if that helps. Also I have my fans on manual switches and turn them on as needed. But I get zero cooling from the fans running.

The only thing that helps is down shifting and hitting higher rpm's (spinning the pump faster). Temps just plummet when I do this. Then when I load the motor back up and run lower rpm's temps climb back up. But never really over 215ºF.

I think my thermo is not opening all the way and thus the higher pump speed helps with flow. I'll let you all know what happens with a new thermo.

Thanks again!

 

[03Golfer]

If the rad is always cold I wonder if there's a partial restriction, or possibly a path the coolant can completely bypass the radiator. That or the rad may need rodding out (cleaned by a rad shop).

 

[burpod]

The only thing that helps is down shifting and hitting higher rpm's (spinning the pump faster). Temps just plummet when I do this. Then when I load the motor back up and run lower rpm's temps climb back up. But never really over 215ºF.

while that could be the case, it could just as easily (if not more probably, imo) be in the tuning....

if you dont have an EGT gauge.. i would highly suggest one. that would tell you a LOT about how things are running... for a build like this, i would consider that mandatory!

 

[syncrotrev]

If the rad is always cold I wonder if there's a partial restriction, or possibly a path the coolant can completely bypass the radiator. That or the rad may need rodding out (cleaned by a rad shop).

It is a new RAD installed a few months ago.

 

[burpod]

It is a new RAD installed a few months ago.

please, take an 011-001-004 of next highway drive you do

 

[syncrotrev]

while that could be the case, it could just as easily (if not more probably, imo) be in the tuning....

if you dont have an EGT gauge.. i would highly suggest one. that would tell you a LOT about how things are running... for a build like this, i would consider that mandatory!

I have an EGT, IAT, Oil pressure, Oil temp, Boost, and 3 water temp gauges in different spots. + a mounted OBD II scanner/screen. EGT's are below 1000ºF in 1st - 3rd all day. Im running a 1.14 Weddle 3rd, and a .70 Weddle 4th. Being that my 4th is so tall, and with my weight/lift/wind resistance. I can push my EGT's as high as I want on a hill in 4th. But have plenty of power not exceeding 1,100ºF sustained EGT temps with a 1300-1500º max spike for a few seconds if needed for passing and what not.

 

[syncrotrev]

please, take an 011-001-004 of next highway drive you do

Im, guessing this is logging Data? I only have an OBD II scanner, and sadly do not know how to log.

 

[burpod]

Im, guessing this is logging Data? I only have an OBD II scanner, and sadly do not know how to log.

you really, truly, absolutely.. should invest $200 in a VCDS for such a vehicle. i'm sure $200 is a drop in the bucket compared to the amount of $$/effort you put into that nice van. absolutely necessary if you really want it to run optimal. at the VERY LEAST get a $10 vag kkl cable with vcds-lite so you can log basic data. you're pretty much blind as to how your tdi is running without it.

EGT/boost can tell you a lot, but log data combined with that.... is a real winner.

 

[burpod]

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.

 

[oilhammer]

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???