Snow Trac external oil cooler installation

Here's some pics of the external oil cooler I installed on the Snow Trac's vw engine. The oil lines route oil from an aftermarket full-flow oil pump behind the crank pulley, through a mechanical thermostat (H-shaped casting attached to braided hoses), and through an oil cooler mounted in the front grill. An oil filter housing and thermostat sandwich adapter will take the place of the thermostat. A mechanical thermostat allows cold oil to bypass the cooler and filter during warmup, allowing the oil to warm to 180ºF before opening. The thermostat also prevents cold, viscous oil from blowing out the filter body/seal, and prevents possible bursting of the oil cooler as cold oil pressure in VW engines can reportedly reach 300 psi upon starting. There's also an inline thermostat for the cooling fan on the outflow side of the cooler. When the oil cooler alone is not able to cool the oil to 196ºF, then the fan kicks on. Some people make the mistake of installing the thermostat on the inflow side of the cooler. The result is overcooled oil returning to the engine block.

The system works well, and probably gives better oil Tº control than the stock VW oil cooler and thermostat. So far, I've not exceeded 190º so the fan hasn't been necessary. Nice to know it's there though.

VERY NICE! Can you post what you done to date on your motor? HP, after market adds ect? Beautiful engine! I am going to build mine up this summer. Also Bobcat wants to also build up a VW. But maybe not quite as Bad ass as this is! What exhaust system is that?

DMiesner mounted his oilcooler on the right upper fender of his Trac Master. How much cooler does she run now with the cooler installed?

It's really not that bad a$$. Sure, I'll put together a post of what I've done and some issues to consider. I was hoping that someone was going to do the 2.2l Subaru conversion though.

If anything, I'd like the oil temp to come up a bit more quickly and stay up at ~180-190. Oil cooling was never the issue in my case. The issue is that the little cooler in the fan shroud unfortunately doubled as a cylinder head heater. I would see CHT's in excess of 400ºF without pushing too hard at all. With the external cooler I don't think I've even seen 370º, and that's well within the safe zone.

Why is it important? An old VW guru that I know once heated a VW 1600 cylinder head to 450º in an oven. After the head cooled, he rapped it with a hammer and the exhaust valve seats fell out! Keep in mind that any increase in bore size in a performance upgrade results in hotter heads. Throw in the waste heat from the old upright oil cooler and you are pushing your luck. You can take your foot off the gas and downshift to keep things cooler, but then you're right back where you started before the engine upgrade.

I had a prospective Snow Trac owner over from E. Glacier come by on Wednesday and check out my machine. I showed him the pitfall of relying only on the oil temp gauge. While pushing it all out in 4th gear uphill, the oil temp was steadily reading 180º, but I pointed to the CHT gauge which rapidly climbed to 350º! That's not too hot at all , but underscores the difference in what temp. is measured. Anyway, I'll summarize the mods and performance changes.

That is one good looking motor. How much horse power do you think it is putting out?

I could have started an entire thread about VW Engine Oil Coolers, but we'll just try and compress it in here:
Thru the 60's Porsche had a string of winning automobiles that had the lowest rate of Oil Cooler failures of almost any sportscar. That's because VW & Porsche attached the cooler directly to the block without any lines. This improved reliability vastly. I lived in Florida prior to 1967, and at Seebring car after car of every make and model got sidelined or spectacularly caught on fire from an oil leak,...except VW's and Porsches.
Before I got into ST4's and Snow Cats in general, I had about 30 VW's and 9 Porsches. So when I did get into ST4's I already had a bit of VW/Porsche engine experience. I never knew John Muir personally, but I had fairly well memorized his book, and even owned a "First Edition" and a complete library of other Porsche & VW Books.(Spirial Wire bound First Editions of the "Idiot Book" are collectable now!) Anyway I tried several aux oil cooler's on VW's, Porsches, and ST4's. Because the ST4 can be operated at such extreem angles, one can starve the engine of oil by having an auxilery cooler. Stay away from long coolant lines. I tried putting a cooler in the rear of a Trac Master, and there was too much oil in the system. In some positions it would run out the fill, and in others it would starve the engine. Heating and cooling problems with ST4's revolve around the "tin". and fuel/air ratio. I've forgotten where, but somewhere I wrote extensively about this in the Forum. (We need a linc here.) In order to own and operate a Kristi, Snow Trac, or one of those 3 Rare VW Powered Tuckers, one needs to get fimiliar with the principals of VW Air Cdooling. All 3 manufacturers balled this up to some extent. If you live around one of the Arctic or Antarctic Circles this is less of a problem, otherwise get "Knowed-up" on the principals. It could mean the difference between walking home and riding! Timing also gets affected by altitude. If you live and operate at a high altitude, and are not running a Diesel, you should be adjusting the Fuel/Air Ratio as well as the spark advance to compensate for altitude. NOt doing so can result in burning a valve, and total engine failure, as well as a significant power loss.

That article is just called VW Engine. I don't know how to do the Linc, but it details the cooling stuff pretty well. Looks like you could use the "3 silver dollar size holes" under your extractor. Nice job on your "Rig" too.

Heres a link to several LYNDON threads.

http://www.forumsforums.com/3_9/showthread.php?t=13167&highlight=Engine

This is a 1915cc engine. Theoretically, it should put out about 95hp at the flywheel. Torque would be the most useful number because of the chain/gear reduction to the drive axle, but I haven't bothered to calculate it. Anyway, I think the 1600 engine put out about 45-50 hp for reference. In practice, what it means is I can now take off in 3rd easily, 4th if I slip the clutch, and is probably enough of a power boost that it leads to bad driving habits.

cabinboy said:

That is one good looking motor. How much horse power do you think it is putting out?

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Thanks for posting this again Lyndon. I should underscore that if you you have one of the stock engines (1200-1600cc), you should not have to do any oil cooling mods as I have. If your engine is running excessively hot then there probably is another reason such as mixture or leaking/missing tin. Monkeying with the oil cooler is just a band aid in this case, and doesn't address the root cause of the problem.

The original inside-the-fan-shroud upright cooler was in production in VW Type 1 engines through 1970, the first year of production of the 1600cc engine. Whether it was the new, larger engine, or the fact that VW Bugs were increasingly being driven in climates much hotter than a Bavarian summer day, in 1971 VW engineers introduced the first external oil cooler "mod." The "dog house style" oil cooler was an effort to separate the oil cooling system from the engine cooling system by offsetting the oil cooler to the flywheel side of the fan shroud, resulting in better cooling of cylinder #3.

I think most engine builders would say that the dog house style cooler will work adequately up to about a 2 liter engine mod with no need for any other type of external cooler. If you're thinking about putting a "beefier" engine in your snow trac, this is something to consider. This is clearly the easiest setup in principle, and it has the backing of VW engineers...if the doghouse configuration fits. Minimally, you'll have to do some sheet metal work to modify the air intake "horn" affixed to the back of the fan shroud in order to accomodate the bulge of the dog house. In my case, I avoided modifying the horn by adding an external oil cooler up front. I'd follow Lyndon's advice in not making the cooling lines too long and be sure that the cooler has adequate airflow.

Just to reiterate, if you're interested in beefing up an engine to ~ 2 liters +, resist the temptation to go with the pre-1971 upright oil cooler. I did it as an experiment, hopeful but aware of the pitfalls, and monitored #3 CHT with accurate, air-temp compensated CHT gauge/thermocouple. The experiment failed, and I had to move to an external cooler. So...chose between a dog house style cooler, which will necessitate modifying the air intake horn, or go with an aftermarket external oil cooler which will involve some plumbing and possibly tapping the engine case. I'm not thrilled with the idea of having oil lines running around my engine compartment, so I went with top quality braided SS lines and fittings.

Lyndon said:

That article is just called VW Engine. I don't know how to do the Linc, but it details the cooling stuff pretty well. Looks like you could use the "3 silver dollar size holes" under your extractor. Nice job on your "Rig" too.

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Lyndon said:

In order to own and operate a Kristi, Snow Trac, or one of those 3 Rare VW Powered Tuckers, one needs to get fimiliar with the principals of VW Air Cdooling . . .NOt doing so can result in burning a valve, and total engine failure, as well as a significant power loss.

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Words to live or die by. These are simple, reliable machines, but need an attentive operator. People routinely put their lives in the trust of these engines as they are a popular small-aircraft engines, but they have instruments that keep them in tune with engine parameters, and adjustments they make "on the fly" to keep them in the envelope.

Having said that, I think my next Snow Trac will have a liquid-cooled, fuel injected engine like the Subaru 2.2 or 2.5 l. The modern engines are complex but their level of reliability is *generally* very high, plus they tune themselves for altitude, etc. As an example, my wife refuses to let go of her '95 Kia Sportage. Kia is a brand not known for quality, especially in older, pre-bankruptcy model vehicles. Yet at 185k miles, the engine has never suffered a crippling problem, not the mechanics or electronics. The worst thing was a bad spark plug wire.

Lyndon said:

Looks like you could use the "3 silver dollar size holes" under your extractor.

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Would that be in addition to the several hockey-puck sized holes (red arrows) I have in there now ? I took your advice and actually punched those holes last winter hoping that it would result in the needed cooling after I installed the new engine. In my case, it wasn't enough but undoubtedly helped cool the engine compartment. These pics were taken with the engine pan removed, but I also put heat-reflecting cloth on the bottom side of it. My hope was to reflect some of the header heat out through the large holes in the belly pan. This undoubtedly helped an incremental amount, but no siginificant improvement was seen until I did the cooler mod.

Snowcat Operations said:

What exhaust system is that?

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It's just an Empi exhaust header. I had to hack it apart and flip the output flange so it faced the rear of the Snow Trac. I should really take it to a fab shop as a template and have them make up a shiny new one...but I doubt I will.

Good posting, listen to what MTMOGS has to say. This is the 'Real' stuff. Hey, what is MTMOGS anyway? is that a contraction of Mountain and Unimogs? Seems Unimogs always overlap with snow-cat people, off road folks, and military vehicle folks!>
I see your "Silver dollars" now! On one of our Non-Stock ST4's, (Ron Hoffman, lives near Yakima, and runs a 1741 in a 63' ST4), he got a full 35 degree temp drop out of the addition of those holes! Suprising something that simple could have that pronounced an effect.>
We used those cheap automotive Inside/Outsied thermometers, and landed the thermistor/thermocouple ends of several on different spots around the engine compartment. One of the most obvious problems was how hot the fuel line got and that it wanted to boil fuel in the see-thru fuel filter. All ST4's came from the factory with a dip stick type oil temperature sender and matching guage as standard equipment(VDO, all still available). Since VW's didn't come with this feature standard, it suggest that oil temperature WAS a consideration, right from Westermaskiner. I recomend pressure and temperature guages as well as a standard Idiot pressure light.

Thanks for that vote of confidence Lyndon. Just for the record, I'm no VW guru like he is however.

Close... it's Montana + Unimogs, a handle acquired before I owned a snowcat. How about MTMOGSCAT? I see the overlap too in vehicles. Always interesting and clever folks I meet too. My wife calls it the "packrat syndrome" because the packrat (Norwegian Wood Rat) scours it's territory for anything unusual, and then brings it home to incorporate in its nest. I said if I'm a packrat, then she must be something unusual!

You bring up a good point about the "holes." It's the 3rd leg of keeping the VW engine running reliably and cool - engine compartment temperature. This is something that Westeraskmaskiner (sp?) didn't adapt to nearly as well as VW. In the Bug, the engine pan seals the base of the engine compartment and keeps much of the waste heat out. There are too many places in the ST engine compartment, notably around the chains and sprockets, where waste heat leaks back in. Some ST4 and ST4B's have an air horn with an auxilliary fan to pull cool air into the engine compartment. I thought about reversing the fan blade so that it would pull hot air out, of course ducting the hot air away from the clean air intake.

I should be more clear about the effect of the holes. While they didn't effect CHT in any appreciable way, which is more directly related to combustion temp and intake air temp, I have noticed that my engine compartment is cooler for sure, even cooler than the stock 1600cc configuration without the holes. I haven't actually measured the temp, but I can touch stuff in there now without fear of burning my fingers. Also absent are much of the plinking and tinking sounds of hot metal cooling when I shut down. Add the holes!

Lyndon said:

Good posting, listen to what MTMOGS has to say. This is the 'Real' stuff. Hey, what is MTMOGS anyway? is that a contraction of Mountain and Unimogs? Seems Unimogs always overlap with snow-cat people, off road folks, and military vehicle folks!>
I see your "Silver dollars" now! On one of our Non-Stock ST4's, (Ron Hoffman, lives near Yakima, and runs a 1741 in a 63' ST4), he got a full 35 degree temp drop out of the addition of those holes! Suprising something that simple could have that pronounced an effect.>

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mtmogs said:

It's really not that bad a$$. Sure, I'll put together a post of what I've done and some issues to consider. I was hoping that someone was going to do the 2.2l Subaru conversion though.

If anything, I'd like the oil temp to come up a bit more quickly and stay up at ~180-190. Oil cooling was never the issue in my case. The issue is that the little cooler in the fan shroud unfortunately doubled as a cylinder head heater. I would see CHT's in excess of 400ºF without pushing too hard at all. With the external cooler I don't think I've even seen 370º, and that's well within the safe zone.

Why is it important? An old VW guru that I know once heated a VW 1600 cylinder head to 450º in an oven. After the head cooled, he rapped it with a hammer and the exhaust valve seats fell out! Keep in mind that any increase in bore size in a performance upgrade results in hotter heads. Throw in the waste heat from the old upright oil cooler and you are pushing your luck. You can take your foot off the gas and downshift to keep things cooler, but then you're right back where you started before the engine upgrade.

I had a prospective Snow Trac owner over from E. Glacier come by on Wednesday and check out my machine. I showed him the pitfall of relying only on the oil temp gauge. While pushing it all out in 4th gear uphill, the oil temp was steadily reading 180º, but I pointed to the CHT gauge which rapidly climbed to 350º! That's not too hot at all , but underscores the difference in what temp. is measured. Anyway, I'll summarize the mods and performance changes.

Click to expand...

Yes Ive decided on the Subaru swap after many hours of going over the pros and cons. I will swap in the EJ22 Subaru engine. She has 135 hp and 137 ft lbs at 4400 rpms. The red line is 5600 rpm! But I have another Snow Trac in the works for sometime after summer and will just install a vw engine in her. Unless of course the swap goes really well. Then.......

Snowcat Operations said:

Yes Ive decided on the Subaru swap after many hours of going over the pros and cons. I will swap in the EJ22 Subaru engine. She has 135 hp and 137 ft lbs at 4400 rpms. The red line is 5600 rpm! But I have another Snow Trac in the works for sometime after summer and will just install a vw engine in her. Unless of course the swap goes really well. Then.......

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Good deal! I'd like to see it. Will you use the stock ecu with a stripped-down harness, or will you go with an aftermarket computer? I was looking forward to doing the subaru swap and read up on a lot of the engine managment issues. Once I started learning about how all those sensors work together it's not so intimidating, and its actually very logical.

As I recall (and take *that*with a big grain of salt), minimally you really only need are the crankshaft position sensor, mass airflow sensor, and throttle position sensor. The crank sensor tells the computer where on the stroke cycle the engine is so it can then tell which injectors to inject and when, and tells the coils when to send a pulse to the ignitors. The EJ22 uses a "wasted spark" ignition so that 2 coils fire 2 cylinders at a time, one one the ignition stroke and one on the exhaust stroke. This helps burn up any lingering exhaust gases. The air flow sensor just tells the computer how much air is coming in the intake, and the computer figures out how much fuel to inject per volume of air. Different aftermarket computers let you program fuel injection maps, and often have stock ones available. No more worries about carb jets etc. An aftermarket computer should use the original 4 ignitors as well. Of course using a pre-wired stock computer is the easy way to go, but I'd check into what the fail-safe modes are for different sensors.

I think you will have fun doing the conversion. I'd like to try it some day.

The company I will buy the engine from also sells a wire harness for the engine. They are used in aircraft as well as in other applications. The wire harness they sell makes everything that much easier!

Are you buying from the outfit in Denver?

Yes I will.