Running Hot

[jimcrazy]

this may sound silly but is your rad fan working?

[dlb]

technically speaking, i would say you have a bit of a shitstorm on your hands. multiple problems that make it harder to determine what problem is causing what symptom. nothing to do but work through each system one at a time, slowly and methodically.

[Petros]

if the upper rad hose is hot and the lower one is cooler, than yes, the radiator is likely working. there is also a very rare time the water pump goes bad and is not pumping coolant, but usually they just get leaky seals because the bearing is wearing out. That would be the last thing to look at, if it is not leaking, the pump is likely doing its job, just leave it for now.

Also, check out your lower hose, after it is warmed up (t-stat is open), rev the engine while looking at the lower hose. It should not collapse, but keep it's shape. Sometimes the stiffness goes away on the lower hose, it must stay open when the pump sucks coolant or it will cause overheating. This is not common, but sometimes the hose is not rotten, does not leak, but gets soft and mushy, causing coolant starvation. A bear of a problem to locate if you have never seen it before.

[Paultercel]

What if the temperature gauge rattles around a lot when driving over bumps? Could that indicate an electrical problem?
My radiator fan wasn't working until I adjusted the carb... After I got that nice humming idle, Both radiator and engine fan started working again... Is the temp gauge wire green/black? I think wire at the front of the engine on that pipe? if so I noticed that the plastic has a crack in it where the wire is exposed... Could that be causing the temperature gauge to malfunction?

[dlb]

if the temp gauge bounces around while going over bumps, i think it's very likely an exposed wire.

the temp gauge wire connects to the engine at the front of the head. it just slides over a metal tab. if the wire sheath is cracked or broken anywhere, allowing the wire to ground out on other parts of the engine, it will cause temp misreadings.

there is only one fan, the radiator fan. it is not connected to the carb at all. it should only turn on when the engine starts getting hot, somewhere just over halfway on the temp gauge. this usually only occurs with excessive idling as in stop and go traffic.

[marlinh]

Does the temp gauge jump around if you tap on the instrument cluster? I have seen that a few times.

[shambug]

Put in a new temp sensor and checked the wiring as best I could especially at the firewall but I cant see any faults. I adjusted the idle fuel mixture to run a little richer and that seemed to fix the overheating, the car will diesel when shut off though. I believe Petros may be right about the head gasket because I am slowly losing coolant without any leaks I can find. It does not smoke very much when turned on, a little more now after adjusting the fuel mixture. Is there a definitive test.

[dlb]

idle fuel mixture only affects the fuel mixture at idle. it doesn't do anything to the mixture while actually driving. that is determined solely by the size of the jets. so if it's running cooler now, it's incidental.

i think i already listed some definitive symptoms of a bad head gasket earlier in this thread.

[irowiki]

What you have there is the best sign, other than a cracked block or head of course.

You can get testing kits that will try to test for exhaust gasses in your anti freeze.

[shambug]

The car never overheating when idling, and if the temperature started to rise I could let the engine idle and the temperature would go down. The car would only run at 30mph without overheating. The over heating did start right after I adjusted the mixture so not knowing where to start, or that it only affected idle, it seemed reasonable. First adjusting the idle fuel mixture by 1/4 turn allowed me to get to 45 without it starting to overheat. I then turned it 1/4 more and the overheating has stopped. All these test drives were within about 3 hours of each other. The weather here has much improved over the last couple days and in the past whenever it was warmer out the car did run a little cooler. I will try and return the idle mixture and see if it was just a coincidence. If it was, I guess im back at square one.

dlb, I did read your list of symptoms and that was helpful. I did take out the #1 and #2 spark plugs and shine a flash light to see how shinny it was in there, but I don't really know how shinny its supposed to be. I would say not mirror like but shinny like sheet metal, and I did not see any carbon build up, although I cant see very much. I am going to get a tiny dentist mirror and post some pictures of the inside of the camber. I did notice a small amount of smoke/water vapor coming from around the exhaust in the engine bay and I still hoping thats my coolant leek although no coolant is found when I run the car on top of cardboard, and all hoses and clamps are new. I will be getting one of those testing kits soon so ill know for sure.

[Petros]

is your timing set properly? retarted timing will cause it to run hot, set it at 10 deg BTDC (rather than the factory 5 deg), borrow or rent a timing light from Auto zone, O'Reiley's or similar.

you have to eliminate all sourses first, before you take it apart, just to make sure.

[shambug]

She overheated very quickly this morning and when I turned the car off I could see bubbles coming up from the overfill tank. I ordered a new head gasket and it wont be here till Tuesday. I printed out Petros head gasket repair guide and got to work. I have the head bolts out and im going to remove the head tomorrow so I can get help lifting it. Anything I should do well I have the head off?

[irowiki]

Check the condition of the timing belt, if it looks marginal you may want to replace it while you are in there. Also how does the water pump look, does it turn smoothly? Thermostat?

[shambug]

The water pump is the only one of those not new. It doesn't spin as freely as my last one but theres no grinding noise, or leakage. I got it for free and it came out of the junkyard. I only used it because it was still attached to the water pump housing that I was replacing. The hood had been left up for awhile so it was a little rusty on the outside but inside looked good. It has given me 3 mouths of service. Worth replacing? could it be the source of the overheating, or could the bad head gasket itself cause the overheating?

[irowiki]

I just like to bring up everything in the front area. Any oil leaks? Valve cover gasket? How does the tensioner spin?

It is easy enough to replace the water pump later so I would not worry about it yet if you have replaced that already.