oil cooler

[tmk]

Where is the best or the easiest place to mount a oil cooler. I have seen them in the motor cover but that looks like it would be hard to get into the compartment. I do not like running it all the way up to the front(Long lines make me nervous). So where to mount?

[Joe Bob]

I put mine in the rear trunk, mounted over a hole cut above the transaxle. The unit is out of a 930 with a fan and thermostat. The fan kicks on @212F/100C. Dropped the normal operating temp 20 degrees.

[iustasail]

Depending on how big the cooler is; there is enough room for most, just barly, to mount the cooler to the right of the trans under the trunk floor above and behind the right drive shaft. The left side will not work due to the starter. If the cooler is short and wide then it should fit with the in/out fittings forward, but this does make the lines take a hard bend to get around and below the engine sheet metal. The good thing is you do not have to worry about the right rear strut and spring grabing the lines.

My oil cooler was to long to mount this way. I had to mount it sideways angled a bit forward. The forward oil line is about three inches forward of the right strut and has no clearance issues. The line runs over the right manifold heat exchanger and behing the right trailing arm caset to the sandwhich plate at the oil filter. The second line runs from the shandwhich plate back the the rear fitting on the oil coolert and if left to its own would put itself right in the coil spring. (Not good, big leak fast!!) so I made a routing guide(out of thin aluminum sheet metal) that leads the line to the inside of the spring along the structural ridge that runs behing the spring and strut assembly.
It works quite well here in Houston!

[John Rogers]

Front is the best, more air, cooler air, etc. If you use the braided lines there is little chance of a leak in the driver compartment. But you will lose some front trunk to the mount and ducting. The inletis usually an opening in the front bumper area for an air inlet and the outlet can either come up through the deck lid or down through the spare tire area. I have seem several others mounted behind the engine beside the transmission with a screen to protect it and stood off from the trunk with spacers, check out the 914 Lite web pages. These are like the ones mounted on the engine cover in they have to have the fan running. I guess you could make the oil lines long enough so the cover could be laid on the top or rear deck lid(no hinges) when doing maintenance otherwise you have to bump into it. Good luck.

[Dave at Pelican Parts]

Check here for one example of the cooler in the back:

http://www.pelicanparts.com/techarticles/914_ext_oil_cooler/914_ext_oil_cooler.htm

Agreed that the front is the "best" in terms of actual cooling. But you need some ducting or a shroud to make it work effectively, otherwise the air mostly goes around the cooler.

The engine-lid version is proably the least-effort solution; the front trunk the highest-effort one. Mine is going under the rear trunk floor when I get it in; I feel that is a pretty good compromise.

--DD

[joncdeke]

I just had my 2.0 professionally rebuilt at Black Forest in San Diego. They did a fantastic job! They mounted the external oil cooler under the rear trunk floor.

Jon

[PeteD]

Thanks Dave for pointing out the article I posted about oil cooler installation.

As I note in the article, longer oil lines equal greater areas for potential failure. Also, when you change your oil, draining lines that go all the way to the front of the car would be a real pain.

Putting the oil cooler under the trunk, with a fan works very, very well. The key is the thermostat system detailed in the article.

YES, I still have a FEW thermoswitches available for $12 including postage.

Pete, dublerfamily@earthlink.net

[tmk]

Thanks to all. I will have to get a new cooler as the one I have is too long to go in the place that is shown in the tech paper.(about 4"x20"). Will a cooler for a auto trans work? I can get from local parts place with fan for about $75.00.

[PeteD]

There are quite a lot of things out there that call themselves coolers... To my way of thinking, a flat plate type cooler, rated for the pressures a cold engine can put out, is the only way to go. The Mesa brand or similar coolers, as shown in the tech article are reasonably priced via mailorder and are pretty much bullet proof. The copper tube with aluminum fin coolers are not nearly as efficient and more easily damaged. Tranny coolers are not rated for the higher pressures typically.

As for fans, get a quality unit like a Permacool and expect to pay for it. See prices in the parts list of the tech article.

If you are going to go to the trouble of putting in an external cooler, don't be penny wise and pound foolish. Do it right or wait until you can save enough to do it right.

Good luck and have fun!

[roadtrp204]

An automatic transmission cooler will not substitute as an engine oil cooler. The internal diameter of the tubing is what makes the difference: tranny cooler 5/16 ID; oil cooler is at least 1/2 ID. The heavier viscosity of engine oil will not flow well enough in a tranny cooler to be efficient in cooling.

Some things to keep in mind when installing an oil cooler are to avoid the use of tight 90 degree fittings or fittings that reduce the ID of the line, and try to keep the cooler at or below the level of the engine.

[tmk]

Thanks to all. I will go with the Perma-Cool Maxi, 900 cfm fan, 3 3/4 in. depth x 10 1/2 in. height x 14 in. long, $131.95 from Summit Racing Equipment.

[paulhagedorn]

As for the motor oil being a higher viscosity, that is not true. Gear oil is genreally about 90 weight...whereas engine oil when hot is anywhere from 30 to 45 in normal applications.

There is a lot more flow and pressure with an engine oil because there are the pistons pounding the oil into every little gap it can go into along with an oil pump, though.

A transmission cooler has thinner tubing to save on weight...or at least the ones that I have seen and are not pressure rated like oil coolers.

Paul

[Dave at Pelican Parts]

Paul, the "weights" listed for gear oils and engine oils are effectively two different measuring scales.

If I remember correctly, the main difference is the temperature at which the oils are measured. Motor oils are measured at something like 180F - 210F, while gear oils are measured at 60F or 70F. This is due to the different environments that the two types of oil have to work in. The motor oil lives in a hot motor, while the gear oil lives in a (relatively-)cool transmission.

If I remember the graphic in the article that I read all those years ago, light-weight gear oils and mid-weight motor oils have about the same viscosity under the same circumstances. I think that the heavy-weight gear oils were thicker than the heaviest-weight motor oils, but I'm not completely certain. (And who runs straight 50-wt oil in a street car, anyway?)

--DD

[paulhagedorn]

Hmm,

Well, ya learn something new every day.
Thanks for the enlightenment Dave.
Another question though...do transmissions that have oil coolers have pumps to run the oil through the coolers or is it just the spinning of the gears that causes some flow?

To me, it would seem as though there wouldn't be much flow in a transmission oil cooler. But that is just a guess on my part.

Paul

[mike mueller]

Most tranny coolers are for automatic tranny's which have a fluid much thinner (cheap pancake syrup) than the manual trannys
(good thick honey)
the auto's get much hotter due to the torque convertor, and friction of the disks. the torque convertor acts as a pump.

for a manual tranny you would need a pump for the fluid to go though the cooler, internal pressure might get some fluid to flow into the cooler but you'd need something to overcome the pressure to get the fluid to flow back into the tranny from the cooler. to the best of my knowledge a manual tranny would be considered a wet-sump since a few of the gears sit in the fluid, as they rotate it flings and transfers the fluid to the mating gears.

------------------
Mike Mueller
Antioch, CA
1970 1.8

[PeteD]

Well, we are drifting a bit here, but what the heck...

The reason automatic trannys have coolers on them is that they generate lots of heat due to the nature of how they work. They have "slip" buildt into their very design and function. That means friction which means heat, and lots of it.

Typically trannys are cooled by having their fluid passed though a second set of coils buildt right into the cars radiator. For bigger loads, like my 34' motor home, a secondary cooler is added in series and is placed in front of the radiator.

Once again, get a quality flat plate type oil cooler. The Summit and Jegs deals are good for that kinds stuff.