Engine Coolant Bleeding

My poor Ranger (ALH | 1749VB | Race520 | Stage 4) was still over heating during heavy shenanigans. Everything in the cooling system is new - VW MK3 radiator, new water pump, t-stat, temperature sender and even an external oil cooler and the overheating was getting worse over time and I was starting to notice some coolant loss - so off with it's head as this really sounds like a head gasket issue . . . The valves all look good, as do the pistons so off to the rebuilders to see if there are any issues with warping and get them to clean it up and do a re-install this weekend.

I was noticing with the head off that the pulley side of the engine is up 5 or so cm higher compared to the flywheel side of the engine. So is this something I need to worry about when adding coolant? I really want to solve this over heating issue once and for all. Is it going to self bleed or do I have to bleed the system with the engine higher on the flywheel side than the pulley side as there is no coolant output on the pulley side to purge air as there is on the flywheel side? Is there a "simple" way to add a bleeder screw to the belt side of the head?

buy yourself a vacuum cooling system filler, it evacuates the system and uses that vacuum to suck the coolant into the engine from a bucket or jug, I use it on everything water cooled including all the audis and other PITA cars that I do cooling system work on. Wish I had it when I worked on Fiat Spiders, those things require jacking the front end up in order to bleed the radiator! Fix it again Tony!

GTiTDi said:

buy yourself a vacuum cooling system filler, it evacuates the system and uses that vacuum to suck the coolant into the engine from a bucket or jug, I use it on all the audis and other PITA cars that I do cooling system work on. Wish I had it when I worked on Fiat Spiders, those things require jacking the front end up in order to bleed the radiator! Fix it again Tony!

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What product to do you use? Do you have a URL to where one can purchase?

Thanks!

I got mine from the tool truck...through a Mac distributor..this is the exact one I use,
made by Robinair, the big HVAC tool company
http://www.tooltopia.com/robinair-7...E7o2nUkwSCMyUeXORwz9KuoQaQrd-a_maMaApFX8P8HAQ

Got the Ranger on the road again and I have no over-heating issues.

I replaced the head gasket and also head the head rebuilt at the same time. Besides valve guides being a little worn, all was good with the head with 272.000km on it.

I have had the truck out several times and drove hard with no issues, but unfortunately three things have changed, so it's hard to say what was the actual "fix" for the over heating I was experiencing.

- New head gasket
- Ambient temperature between 0C and 10C
- Vacuum cooling system filler

Now, I am going to start to put my money on the vacuum cooling system filler. For those who don't have one, it's one of those devices like a shop compressor - you can do everything without it, and once you but one, you can't imagine life without it. That tool is bloody awesome! I would say this was the fix because besides standing the truck up on it's nose, there is no way you can get all the air out of it to fill it with coolant and I am sure those voids were what was causing the issues. Also, filling the system is SO much quicker and you don't spill a drop. I bought the Robinair unit below - quite happy with it!

Right on! Glad I could help

Vacuum evacuating the system works better than not, but there is still a problem that develops slower over time. The engine is too much of a "nose up" slant to get every bit of air out of the head and you guessed it, the overheating problems are back.

I think my only solution here is to install a fitting into the belt side of the head so that there will be no air lock.

Does anyone have a good knowledge of the cylinder head and where one could drill and install a 1/4" brass fitting that would go to a pipe that loops back to the coolant bottle?

Im just trying to think this through but if you pulled all the air out ( vacuum or idle at operating temp facing down hill) Then in a intact system there shouldent be any air getting into the system as long as your overflow is full correct? If thats the case do you think you could be lifting the head in certain conditions during boost?

David,

Although my engine tilts slightly down on the pulley end toward the rear of the Van, I believe the water pump pushes coolant through fast enough to move air out.

Here is why I believe the coolant flow is adequate to push the air out of the block and head.

I have a Coolant System Pressure Gauge installed. I tapped the top/side of the round expansion tank for the direct fit of the tube to the gauge mounted below the dash in my Vanagon. Once the engine is warmed up to normal operating temp, pressure ranges between 7 and 9 psi... mostly toward 9 psi.......... depending on ambient temp, I've seen 11 to 12 psi. The gauge max is 15 psi.

Anyway, the gauge is very sensitive to pressure change inside the expansion tank. I can rev the engine and watch the pressure drop 3 to 4 psi immediately and then settle back to where it was. A repeat tap of the accelerator and the pressure will drop again, etc.

Point is, the Water Pump is sucking/pulling coolant out of the bottom of the expansion tank faster than the smaller hose can replace it, which reflects the efficiency of the pump.

So, as I stated above, my thought is the movement of coolant should be sufficient to push any air out of the block and head rather quick.

Lastly, after filling the cooling system the first time, including bleeding the rad up front at the small bolt, I've never bled it again. When I've had to drain coolant (with use of vacuum), I've always put back the exact same amount that came out. Based on that procedure, I've always assumed the system had enough coolant to do the job. It has never over-heated.

Motohead1 said:

Im just trying to think this through but if you pulled all the air out ( vacuum or idle at operating temp facing down hill) Then in a intact system there shouldent be any air getting into the system as long as your overflow is full correct? If thats the case do you think you could be lifting the head in certain conditions during boost?

Click to expand...

The thing is your engine is continually generating air in the coolant which needs constant dearation or it will build up in the system...even with a sealed head gasket.

David, I'm in the same boat as you. I've got a junk head here and will look into where a tap could be added which would pierce the water jacket on the belt end of the head. Likely the only available location would be just ahead of the intake manifold.

Do you have a plastic or metal water pump impeller? We have found that the plastic ones are much more efficient. We have had overheating problems and no heater at idle situations in beetles in particular. The engine would overheat and the heater would be cold due to poor circulation, particularly at idle. The cure was a plastic water pump, which is all we like to use now.

I honestly can't remember what material the pump is. It was replaced in the summer. New radiator, there is no obstruction in any of the hoses, no collapsed hoses and when the system is full of coolant and bled no issues, just gradually pukes a little bit of water out the VW coolant bottle here and there and soon I'm down a few liters of coolant.

The cylinder head was rebuilt this fall, really no change in how everything is operating. Right now with a bled system lots of cab heat, engine sounds normal and the temperature never goes about 92C.

greengeeker, very interested in what you discover as to where to install a vent. I have an AHU head here, but no spare ALH.

David, do you ever hear gurgling through the heater core after shutdown?
Ever sent a coolant sample in for exhaust gas analysis?

when you say 'soon' for needing a couple liters of coolant, how soon is soon?

You may seriously want to consider upgrading that radiator to one from a V6 Ranger. The MK3 Jetta radiator is most likely not up to the task of dispersing the thermal load put on it by the diesel pushing a much heavier and less aerodynamic vehicle. The MK3 TDI radiator is small !! I know I have had a couple.
In addition since this is a conversion are the cooling circuits properly sorted out? Is the flow going in all the right directions? Do you have a faulty gauge....or have you verified the accuracy of the over heated alert with a secondary gauge for confirmation?

A higher CFM fan maybe?
When summer comes I'm going with a 14" 3000 cfm fan,
it has a 2600 now hoping that will drop temp down below
208 when putting a load on it.
Not related but when I first plumbed my ALH I had the flow backwards for about
100 miles before realizing it was wrong,since reversing it,it now runs on the average 2 to 4 degrees hotter.????

When it is low on coolant, yes, you can hear some bubbling when you shut it down. I added about 2L here and the last bleed was in October when I did the cylinder head. So about 4000km or so.

The thing is, the rad doesn't get all that hot. I've never had the rad fan come on! The hose to the rad is hot and from the rad is hot, but the rad itself is always cool to the touch. Yes, new radiator installed and the MKIII rad I think is plenty big as the Vanagon rad isn't much larger and I have never had over-heat issue with this. New t-stat too.

The temp sensor was replaced when I did the head. Both the coolant gauge and the ECU are reporting that things are hot and I would agree that they are hot.

Right now with the system bled, it won't get to operating temperature on my 13km drive to my day job. Usually about 82C or so by the time I get to work. Quickly gets to about 60C - within the first km and then slowly climbs.

Just so we are on the same page, I am going from the cylinder head to the top input of the radiator. The top input has a tee in it that takes the 1/4" hose to the top of the coolant bottle, this is also Teed in with the cylinder head. The radiator is upside down so that the ports are on the driver side, I really don't think the internals or the rad would restrict flow.

Wont get hot on a short drive... but it still over heats....

Textbook... get another new thermostat. Its not unheard of to have bad thermo's out of the box. That or its incorrectly seated or even backwards.

I looked at my spare ALH on the back room and I see the bleeder on the rear. I tried poking a wire into it to see it it went straight through to the front where you might be able to drill a hole. Of course it doesn't. We had it apart all winter waiting for a spare moment to finish the engine, I wish it was apart to be able to see the passages, but it isn't.

I would try bleeding it with the nose downhill enough to release the trapped air. Though I would think just driving down a hill would do it while running. Kinda like trying to get all the air out of a Vanagon waterboxer first try. Usually after a few hills they burp out too.

Is your coolant tank higher than the radiator? and engine? Sometimes on the Passat, A4, A6 I loosen the coolant tank and elevate it to get a good bleed.

Yeah, the "max" line on the bottle is higher than the radiator and the cylinder head.

The t-stat *should* be installed correctly. I know it does work as I put a pot of water on the stove and boiled it first - it need opens before the water starts to boil.

So yeah, on the way home 105C. So I immediately loosened the clamp at the top of the radiator and there is an air pocket there... so it too in another 500ml of mix today.

This got me thinking. Should I put the Ford overflow back in and that pressure t-valve and just let the system suck in and belch out the coolant that is needed with the T-valve right next to the rad at the highest point in the system.

This is really bothering me - I have done so many engine conversions and most in Vanagons which can be a challenge to bleed, but this... aaaagh!

FWIW, as I noted in my other post, I installed a coolant pressure gauge system in my Vanagon with the ALH engine.

Well, about two or three days into the 2014 road trip to Alaska, I noticed the gauge was on zero. The tube on the back of the gauge had slipped off (no clamp).

So, for the balance of the 33 day and 11k mile trip, the coolant system was not pressurized. No over heating at all... and, I did not have to add coolant.

I do not buy the thought/theory that air is constantly needing to be purged from the system. I agree with motohead1, if the system is full of coolant, air purged, then it should stay that way unless air is getting in somewhere. Either a bad head gasket or crack in the head that's allowing exhaust gasses to seep into the water jackets of the head. I doubt that the water pump is strong enough to suck air into the system via hose fittings or the one O-ring on the return small steel pipe at the back of the water pump housing on the block.

If allowed to sit and idle for some time, the fan on my Vanagon will kick-on! From the engine bay, it has the OE pipes, rad and fan with a new sensor switch. And, as I stated previously, I've never had an issue purging air out of the system....

Seems the routing of your hoses is okay.

So, I believe you have a rather major problem... most likely it's the head!

There is just one little piece of the puzzle missing and causing problems I am sure. My guess is the coolant bypass flow has an issue. If I read correctly you have the bleeder off the head connected to the tee in the upper hose and the top of coolant bottle. I would try blocking off the hose to the upper hose tee and run just the bleeder to the bottle as an experiment. Do you get flow from the breather hose to the bottle with the t-stat shut? My thought is that the tee in the upper hose could allow air to be sucked in from the top of the coolant bottle at times, and eventually air locking the system. I do agree that a bleeder on the top of the radiator is a good idea for initial bleeding, but once bled it wouldn't be needed anymore.

I know this is a different car and all, but I have had cases on Subarus where the people have given up on them after replacing the headgskets more than once to cure overheating. they do have headgsket problems for sure, but twice in a row? I found on two different cars the same problem, random overheating and coolant loss. The coolant bypass on a Subaru goes through the heater core, so when the t-stat is closed the water circulates around the engine and is sent through the core and sucked back in by the pump, this creates a circular flow through the engine. If the core is restricted the coolant does not go through the bypass and just remains in the engine not really moving and cooling. The thermostat will not sense temp and open because it is sitting in relatively cool place without the hot water circulating. If easy driving it might get enough heat by convection to open the t-stat, then the radiator will function normally, till the stat closes again. Thus purely random overheating, or so it seems. The engine can be boiling but the radiator is cold. Once I restored good flow through the core allowing the water to take a designated path during warm up, the cars worked perfectly. Since then I blow through the core of any subaru I have the coolant out of for repair, and monitor the hoses on warmup after filling to be sure there is flow and that it is bled. Never another problem with them now that I understood the physics of it all. I tried to explain my findings to my Subaru tech to help him avoid the issue and he argued many times that I was full of crap, till I fixed one that was giving him a lot of issues by flushing the core.

I may be truly full of crap, but there has to be something causing your issues and that is all my pea brain can come up with now. You might still have to initially bleed it nose down, but once bled it shouldn't matter if the air ingress is stopped.

Do you think your burning antifreeze?

Condensation at the tailpipe after a long run?

You can pull your glow plugs and look for one that is cleaner than the others...an H2O indicator.

The other thing is pressure test the cooling system.. let it sit there for an hour at 25-28 psi. If in doing so you notice a drop in coolant and you cant find it, I strongly suggest you hand crank it 4 full revolutions before using the starter. If its a Head Gasket or even a cracked head this will expose it. If you think your sucking in air(unlikely)...where ever that is you will certainly push coolant out of it at that pressure.

Another thing is to check your oil temps.. that will indicate the condition of your oil cooler.... which also begs to ask... have you checked the oil lately for anything unusual?

The only time a coolant system can make air is if your boiling the coolant.

Or head gasket /surface issue.

Or hairline tiny crack from exhaust valve guide to water jacket that dosent show up untill full operating temperature and only then does it show up after driving all week when the low coolant light comes on and then the only way it was found was after headgasket job number 2 to fix the issue the head pressure checked fine but your old guy machinist suggest to flip the head over and put varsol in the coolant jacket and sure enough after a few minutes at room temp you could see the stuff leaking very very slowly into the exhaust port from around the valve guide.


That last example was a once in a lifetime. How it did not leak down on a pressure test I dont know but the varsol trick works.

the front of my head is much higher than the rear and i've had zero overheating issues even in 100*+ temps, towing, high altitude, high speed...nothing budges the temp above 95c except when i had a super hot t-stat which i switched out for an 87c unit a few years back ... also no issues on the initial bleed ...also i considered moving the bleed nipple to the front of the head to assist in air purging but it has not been an issue

I figured out the issue this time -well I hope did anyhow!

I got home Friday doing about 70km/h and the temp got up to 107C and there was no cab heat - ***!!! Pulled into the yard and I was getting a little angry at the situation. How could I lose that much coolant in such a short period of time? Visions of removing the head again and spending even more money on this truck and more down time when I have no 2nd vehicle at this moment. I start wiggling hoses to see if there was any coolant leaking anywhere and then PSSSSST! Turns out that the hose clamp at the fire wall for the heater wasn't done up tightly. I remembered that when I was removing my cylinder head I went to undo this one and the hose wouldn't budge so I remove the hose from the head instead - apparently I didn't tighten the clamp and over the winter here the hose did work itself loose. Thus the source of the me losing coolant again and overheating.

So.... it's all bled and topped up - let's see what happens this week.

The littlest problems can cause the biggest headaches.

LOL do you even have a coolant system pressure tester?

good work ... i just spent half a day diagnosing a bad t stat housing ... turns out it was a crappy meyle aftermarket unit the customer swapped in last year ... i steered away from it being bad because customer said it was fairly new ... i do have a new cooling system pressure test adapter for an mkiv now ($61!!)

1.9ZOOK said:

The littlest problems can cause the biggest headaches.

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X1000! and most of the time it's almost a fluke to find/ stumble upon.

OH, but the feeling of elation, or embarrassment after finding it is SWEET!!

Ranch said:

X1000! and most of the time it's almost a fluke to find/ stumble upon.

OH, but the feeling of elation, or embarrassment after finding it is SWEET!!

Click to expand...

I don't mind admitting I flamingoed up! It's when you don't admit it, is where there is a problem.