Syncro + Subaru Cooling Issues

[dobryan]

[PDXSyncro]

Hi Wesitarz,
Yes I replaced the pressure cap and even put a new one with only 13psi as the previous one (also quite new) was 16#. For some reason the "Tank" is sold with a 16psi cap. Anyway as the SVX was 13# I thought I'd try that. Did not seem to change much.

Ya I thought as well to check for a head gasket leak but if it is it's an insidious one as I've driven a good drive around town, let cool and then tested the coolant for combustion gases and nothing showed up. But again that might be that it needs the rev's and elevation. Which is what struck me about this thread in the first place. The PO was seemingly having the exact same issue, only apparent on seemingly long drives and elevation.

That's one of the reasons I asked about the air intake gasket as I had removed the air intake plenum a while ago and wondering if maybe air could be getting into the system from the gasket! As there are 2 sets on the SVX.

The second thing of note is I seemingly have a vacuum leak during acceleration as there is a loud whistle during acceleration, sometimes decel as well and usually when turning the engine off. I had visited Tom Lengyel a few months back regarding this issue and he said that he thought it was a seal on the butterfly valve causing the vacuum leak and the whistle. The same seal as discussed in this thread:
https://www.thesamba.com/vw/forum/viewtopic.php?t=674822&start=0

I would think however that if there was a leak in to the coolant that coolant would then also leak into the air intake and combustion chamber and I would be experiencing other issues. If so those issues are there they are very slight. On listening to the engine there is maybe a small misfire from time to time and it definitely has the SVX ooomph but maybe a slight noticeable decline. Anyway hard to establish a real baseline on this. The heads were decked and new valves done about 15k miles ago.

Thanks!

[wesitarz]

Have you inspected the coolant lines to and from the throttle body? Maybe try bleeding over several cycles/days around town before a high rev mountain trip to make sure you have bled all the air out? Yes intake gasket leaks can cause issues. Did you replace with new ones? Good luck.

[PDXSyncro]

[PDXSyncro]

So I tested after securing the hose from the manifold to the TB better, checked for pressure loss and there was about 1 PSI loss over 2 minutes. Which didn't seem like a ton but was definitely loss. Anyway I took it on a trip and I still had air getting into the cooling system on trips over an hour and up hills. I took the Westy to SmallCar as they are the experts in SVX and they confirmed a leak in the engine so they're pulling off the heads and going to test them. They are also going to reverse the coolant manifold as well to shorten the coolant travel from around the engine. So that's that! Now whether it's a gasket leak or a crack in the head I have yet to find out.

Anyway a big thank you to those who offered up advice and ideas! It's great to have this forum of folks to turn to!

Cheers!

[20.6N87.0W]

[68kmgvert]

Trying to revive this post for some help. I have a Syncro with an SVX engine that is having cooling issues. It has always been fine heat wise on relatively flat terrain but when climbing sustained steep passes it gets very hot and can over heat. I have a new Behr radiator, SS coolant lines and new thermostat. The cooling system seems to be functioning normally. I had hoped to find an upgraded all metal radiator but couldn’t find any that people had used in Vanagons. Currently thinking of trying to put in shielding on the exhaust system and/or doing something to try to increase airflow to the engine bay. Any ideas or advice would be greatly appreciated.
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1968 Karmann Ghia Convertible
1979 Beetle Convertible (Epiog)
1987 Syncro GL Westfalia 3.3 H-6
2011 Touareg TDI
2013 Golf TDI
2015 Golf TDI

[4Gears4Tires]

https://www.amazon.com/Hylaea-Outdoor-Cooling-Port...amp;sr=8-5

Add a misting loop to your radiator?
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'87 Syncro
Ferric Oxyhydroxide Superleggera Edition

[J Charlton]

The cooling / overheating issue with Subaru engines in vanagons is not unique to Syncros. When i was contemplating converting my '85 westy 1.9L wbx to a 2.5L subaru engine I was aware of the heating/ cooling issue BUT I was fortunate to have as a relative neighbour, Tom Sheils. who explained the issue to me - I'm going to synthesize his wisdom and analysis below
1. The vanagon cooling system was designed to accommodate the cooling needs of a relatively inefficient 1.9 or 2.1L wbx engine. It is massively oversized to cool a relatively efficient more modern engine.
Consider : ( I'm going to use my 1.9L wbx / 2.5L suby engine in the same van for comparison purposes and I'm going to "round off" figures to make the comparison simpler)
- my van with wbx engine achieved 14-16 mpg - let's round off to 15mpg
- same van with 2.5L suby engine achieves 22-25 mpg - lets use 20 mpg to be conservative to make the point
This means that the wbx engine uses 33% more fuel (energy) to do the same work. The Law of Conservation of Energy says that ALL energy has to be accounted for. Since the fuel (energy) is not being used to do the work of propelling the van (lets assume same driving conditions , behaviour) where is it going??
The excess energy consumption of the wbx engine is going into the process of generating heat - and the vanagon heating / cooling system is appropriately sized to handle this amount of heat. BUT - if a relatively efficient suby engine is in place, turning relatively more of its fuel into motive power and less into heat, the amount of energy that the vanagon rad and cooling system can remove is far greater than the suby engine needs.
The issue then is that with the cooling system capable of removing far more heat energy than necessary for a suby engine, why do we get overheating?
We get overheating - and the only overheating that is critical - when the coolant temp of the coolant in the engine is so high that it is incapable of absorbing enough heat energy from the engine to keep it at operating temperature
How can we get those high temps when the cooling system is so oversized?
Because the thermostat - that opens and closes to regulate the flow of coolant into the engine - is not reacting to ENGINE coolant temperature but rather to the temperature of coolant that has passed through some or all of the cooling loops of the system - heaters (which are mini rads) or the rad itself. The oversized vanagon cooling system will overcool the coolant to the extent that it will be too low to cause the thermostat to open and therefore not let coolant into the engine - the coolant in the engine itself will then rapidly overheat
Given this - the solution involves ensuring that there is enough flow of engine temp coolant onto the thermostat to enable it to react to ENGINE temp, not coolant loop temperature.
Tom developed a thermostat housing / bypass that ensured that the thermostat was reacting to engine temp - you can see his cooling diagrams at
subaruvanagon.com/tom/Cooling%20System.htm
With Tom's system 4 - or 5 - and his adapter in place the engine temps of my 2.5 subied hightop never vary from a rock steady 185C
Tom knows cooling.
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NAHT hightop availability May 18 2023 -
Bend Oregon - for Oregon, California- (7 tot , 3 available), Kennewick Wa (6 tot, 1 available), Small Car Performance Fife Wa. (7 tot 4 avail ), Fairbanks Alaska (1 tot 0 avail)
Future availability TBD : Springfield Mass. Staunton Va, Florida, Colorado, Grand Junction Co., SLC probably late 2024

[MarkWard]

[harvgwen]

I’m quite new to this Vanagon/Subaru thing, but I learned a little when I added a rear heater core (and so letting a bunch of air into the cooling system). The cooling system itself doesn’t overheat, the t-stat hasn’t even opened so the radiator and coolant in the lines are still cold. I suspect in my case there was air on the top side of the t-stat, so it could never sense warm coolant and never open, even though the engine was getting hot (I shut it down before it got too hot). The normal procedure is to install a small hose that bypasses the heaters and ensures coolant is always getting to the top side of the stat. I know some disagree with doing this, but I drilled 2 1/8” holes in my stat to keep coolant getting to the top of it. This seems to work. I think it does the same thing as a small bypass hose. I got this idea from some Subaru forums. Subaru’s seem to have this same issue even without adding the very long hose routing that we have, making the problem worse.
Tom Shiels mod is brilliant but he isn’t currently making them. Hopefully he will again soon.
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1986 Westfalia Vanagon, 2.2 Subaru
British Columbia, Canada