Overheating 240D

[VW1300]

I am posting this for a coworker who has an '82 240D.

About a week ago the temp gauge was maxxed out at 120 while driving on the highway. He pulled over, turned the engine off to let it cool, and started it back up. He drove home successfully w/o overheating again.

A few days later the same thing happened. Then yesterday, just driving in town it overheated again and wouldn't cool down. He replaced the thermostat, and drove it to work today (some highway driving). The temp was around 100 the entire time until he got stuck in a traffic jam, when the temp went up to near 120. Soon he got going again, and the temp came back down.

When he exited the freeway and slowed down into stop and go traffic, the temp started fluctuating fairly quickly bt 100 and 115. Overall, he feels that the temp situation gets better when the car is moving.

He also noticed that with the car in neutral, and he revs the engine, the temp seems to come down.

He probably could use a coolant flush, which he plans to do, but are they any other ideas on what may be causing this?

thanks,

[P.E.Haiges]

VW1300,

Have your friend take out the radiator and take it to a radiator shop for a clean out. They will do a high pressure flush or steam internal cleaning of the radiator.

This will clean most of the crud off the tubes inside the radiator and it will have better heat transfer. They will also check for any leaks and repair them. This should cost about $40 if he R&R the radiator himself.

If the shop says the radiator has reached its end of life. he should have it recored at less cost than a new radiator and it will have to performance of a new radiator.

BTW, is he loosing any coolant? If he is, a leaky head gasket could be the cause of the problem.

P E H

PS. Why don't U tell him about this website and have him submit his own questions?

[jkoebel]

Fairly quick fluctuation probably is a bad temperature sender or bad ground on the cluster. Mine jumps about 10C increments on occasion, its way too fast for that to be the actual temperature.

What's the good temperature for a 240D to be sitting at? Mine is at about 110C-115C in highway driving, around 100C in city driving.

[rs899]

Mine goes from 82 to 90C- never higher.

[Stevo]

When he replaced the T-stat, that could have cured the over heating problem but if the air was not purged out of the system after the t-stat replacement that could be causing the problem now. Usually with the "later" 240Ds (his) air in the system is not a problem with only a T- stat change. 84C is proper running temp, but 100 is OK above that (except up hill) there is a problem in the system.

[VW1300]

Originally Posted by P.E.Haiges

VW1300,

Have your friend take out the radiator and take it to a radiator shop for a clean out. They will do a high pressure flush or steam internal cleaning of the radiator.

This will clean most of the crud off the tubes inside the radiator and it will have better heat transfer. They will also check for any leaks and repair them. This should cost about $40 if he R&R the radiator himself.

If the shop says the radiator has reached its end of life. he should have it recored at less cost than a new radiator and it will have to performance of a new radiator.

BTW, is he loosing any coolant? If he is, a leaky head gasket could be the cause of the problem.

P E H

PS. Why don't U tell him about this website and have him submit his own questions?

He did register, but for some reason was not able to actually start a thread.

About the coolant - how far up the radiator should the level be? How do we know if it's low? He doesn't have a reservoir which would make it obvious.

[pj67coll]

Originally Posted by VW1300

He did register, but for some reason was not able to actually start a thread.

About the coolant - how far up the radiator should the level be? How do we know if it's low? He doesn't have a reservoir which would make it obvious.

About an inch below the bottom of the filler neck. Mine never went above 90C, irrespective of wether I was idling, or in city traffice or on the highway.

- Peter.

[t walgamuth]

It needs to cover the tubes but not be all the way to the top. It needs room to expand.

I agree that it does not seem as if the radiator is the most likely culprit here.

Tom W

[minimike1]

He and anyone else can run the car with the rad cap on only one click. That way the fluid will not be pressurized and not blow out the overflow but will still circulate and take some heat from the engine to the rad. I'd check to see if he's got air in the system. An air embelism? will make the car overheat quickly. to remove the air, drive the car as above for 35+ minutes to let the water circulate and the air move to the the top of the rad and out of the 1/2 open cap. He should also make sure the heater core is open, heat settings on hot. No need to run the fan motor unless the driver is cold or car starts to overheat during the air bleed. If the car runs hot after that, remove the rad and have it boiled out. or recored.

[dwoloz]

Fluctuating temperature readings sounds like it may be a bad sender. My 83 changes temperature readings very gradually.
He is right though to believe that when the car is moving it will be cooler. The air through the radiator does the most cooling.

[VW1300]

Update:
We decided the logical next step was to flush the coolant system and refill with a 50/50 blend of antifreeze/water. Who knows what was in there? He hadn't flushed it since he bought it.

Given the urgency of the situation, he took the car over to a radiator shop down the street at lunchtime and asked for a flush. While there, they noticed he was losing coolant thru the water pump weep hole, never a good sign...apparently coworker hadn't noticed this.

So now he's on the hook for a new water pump and coolant flush (he has a new set of belts for them to put on while they're there too). Hopefully that will take care of it, he's just happy he wasn't stuck by the side of the road.

I will report back on the outcome. Thanks to all who responded.

[kerry]

I was going to suggest a new water pump since it cooled down upon increasing the rpms.

[VW1300]

Update #2

Water pump was replaced yesterday afternoon. Coworker then made it home fine, his drive to work was OK too. Looks like the problem was solved.

[P.E.Haiges]

I suspect it was the radiator as I suggested earlier. The only time a water pump causes over heating, other than leaking coolant, is when the impeller comes loose from the shaft and the impellor doesn't turn or doesn't turn fast enough.

P E H