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mejulihn's Avatar
 
Join Date: Nov 1998
Location: Camino, CA
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Access to oil cooler

I am still trying to track down the cause of an overheating problem with my '76 2.0 L. I have ruled out several suspects but want to check to see if the oil cooler has collected oil/dirt/debris in the outside cooling fins, reducing its efficiency. What is the best way to visually inspect the oil cooler? Do I need to remove engine tin from the underside of the engine?
Old 01-07-2000, 02:48 PM
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To see/clean the cooler the best (maybe only) way I've found is to pull the tin. This in turn means pulling the dizzy and FI. I've pulled both sides of the tin, the FI, the dizzy, fixed some holes in the tin, painted the tin, replaced the CHT, cleaned the cylinders and oil cooler, cleaned the electrical contacts, sealed the intake distributor, and reinstalled everything in about 6-7 hours of constant work. It actually took from 9:30 am to about 8:30-9:00 pm but I had a long lunch and helped a friend with his car. There really aren't any pit falls except that the 2.0L gaskets can be hard to find so get them first. Also this is a good time to replace the CHT sensor, oil pressure idiot sensor, and the oil cooler seals if need be. Use a wire brush ("'cause it works") and a can of carb cleaner to spray down the barrels and oil cooler. Blow debris away from the dizzy before removing it or the junk will fall down in the hole.

Other things that cause a high temp:

1. The stock temp gauges are off most of the time because there were three different gauges that match with three different senders. The wrong combo nets ironious readings.

2. Engine compartment gasket gone. On my car with the A/C this is really a problem because of how the dealer installed the A/C makes a big hole in the side of the compartment. I patched things up with high quality HVAC aluminium foil tape. A temporary fix until I drop the motor on this car.

3. Too advanced timing, too lean a mixture, and the 75-76 had more smog equiptment which puts more of a thermal load on the motor. (Note: Some off the wall theory I heard from a certain Dr. was that the 75-76 block was made of a different alloy which causes them to run hotter, I asked him what alloy he was refering too, I got no response. Personally I think he was just tring to scare/sell pre 75 blocks to people.) If the smog equiptment isn't running right it can cause more heat, if the cat is blocked, or the air pump air filter is blocked there is a greater load on the motor. Best thing is to retro fit a 73-74 exhaust on the car and remove the air pump (did I say that? I mean if the car is for off road use only ) if that's not fesible try to see if the smog stuff is working.

4. There are some air deflectors on the rear, bottom, of the floorpan. They deflect cooling air into the motor. See if they are still there.

5. If the thermostat fails it stays in the open position. It is possible that it rusted in the cosed position but not likely.


The biggest things are timing, mixture, and the engine gaskets.
Old 01-07-2000, 08:22 PM
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JP,
Thanks for the thorough rundown. I have replaced the stock in-dash temp gauge and sender with a new VDO guage in the center console. The new sender and gauge match. (By the way, the stock temp gauge was also reading high). All of the engine tin and seals are in place. I removed the smog pump completely (until the next CA smog check) and it is a 49-state car so there is no CAT. Timing and mixture are OK. The bellows-type thermostat that controls the cooling flaps has been disconnected, so the flaps are open. I do have AC but can you explain how the placement of the compressor in the lower right front corner of the engine bay would affect cooling (other than the load of the AC drive belt)?
Old 01-08-2000, 08:44 AM
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The fan is designed to pull in cool (cooler anyway) air from above the motor and then blow it over the cooling fins of the cylinders, heads, and oil cooler. If the air is instead pulled from under the motor it is basically pre-heated air that doesn't cool as well. A wiser man than I, Bob Hoover, did some experiments on an aircooled VW motor and found (as I'm sure the VW engineers already knew) that hotter air dosen't flow as well as cooler air, also it has less capacity to absorb heat from the motor. So the more, cooler air the fan gets, the better. I'm far from an expert in thermodynamics so that's about all I can say (i.e. state the obvious).

Look back in the archives, the matter of how hot is too hot has been talked about. Can't remember if 220-230 was the hot mark and 250 was TOO HOT??? In any case if your motor is too hot with the timing, mixture and stock cooling system in good shape I'd agree that cleaning the cooling fins is the next step. Then (if possible in your climate) remove the rain tray, and finally get an aux oil cooler. Doing an aux cooler is a whole other story. IMHO there is a cheap way and there is the right way.

BTW I thought that the '75 49 state car was the last one to have no cat and all the '76 cars had one?


P.S. The placement of the A/C causes a leak in the engine compartment seal. As for the load, if the A/C compressor clutch is working as it should there should not be any load on the engine.

Another odd-ball thing to check is to see that the fan isn't missing more than 4-5 blades.

[This message has been edited by JP Noonan (edited 01-08-2000).]
Old 01-08-2000, 06:59 PM
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