Common Overheating

[RageRover]

Well, with the number of overheating cases I've seen on LRO, it was just a matter of time before it got to me. The karma bit me in the ass earlier today, overheating, according to the gauge, just at "H". I pulled her over, and the engine, was friggen' HOT.

What is weird with the whole overheating case that differs from others, is that she overheats at occasional stops, and just idling in the driveway, after a common across town drive. She then cools off about 5 mins, if any less, later then as long as I keep her moving she stays right at the normal range. It confused the hell out of me. This overheating thing has not just been like this, it started getting hot last Wednesday, but she didn't get as hot as she did today, which was right at "H".

I dunno, what to think. Earlier today, I did a flush on her, got the old coolant out, did a flush, cleaned that all out, and topped her off with brand new coolant. She still overheated later in the day. When I listen closely, I can hear, what sounds like coolant boiling in the hoses. I heard somemore boiling-like sounds from the heater hoses, plus I had the heater full blast going off, so that she didn't lock herself up.

Well, now that I got new coolant in her, the heater control valve works, cause of the tremedously good heat I get in the cabin, fluid moves=water pump works, the fan turns, the front comdensor fans work, the radiator is free of mud or debris. I can pretty much conclude that the thermostat bad? But then again, as I was doing the flush, I filled the radiator with water, with the upper radiator hose off, to see if water would get through the thermostat (the motor was still pretty warm, so the T-stat would still be open) and sure as shit, water flowed out. So what should I think? I mean, a thermostat isn't that much and gasket, and RTV. But what should I look at?

[Badger1]

What's your oil look like?

Does the overflow tank cap still feep good pressure? T-stat? You can order all that from Atlantic British along with the upper engine gasket set...sounds like your going to need it.

[Greg M]

Pat man, you're sure having a lot of problems lately. Sucks!

Anyway, it actually sounds like either a thermostat not allowing enough coolant through or you may be losing your water pump. It doesn't need to weap, and it could still be moving water through the heater but not enough volume through the radiator. I would almost lean more toward this. It may be not able to pump enough volume at low revs.

If its a blown head gasket, from personal experience, it will create A LOT of pressure buildup in the system. so when you take the cap off instead of a little pssst, you'll have a real loud PSSST, and maybe even overflow a little coolant as it bubbles.

[Badger1]

Pat are you noticing any loss of coolant?

[RageRover]

I am not seeing any loss of coolant in the system, at all. Today, she didn't overheat at all, she stayed in the normal range for the temp gauge, right in the middle. But I still wanna investigate, I have to do an oil change, as I am about 100 miles over the change period, in which for me, is every 3000 miles. I dunno what to think, the expansion tank is still holding up, no leaks, no hissing.

Yesterday's issue I heard what sounded like boiling water in the upper radiator hose. When I went to take the cap off the expansion tank, she didn't make a loud hissing sound, just the normal breif hiss and a little bit of coolant, nothing abnormal, and this was shortly after the guage read "H", with teh engine off.

I can assume the water pump is still working and pumping good, as I was in stop in go traffic all day today, and not once did she overheat, or the guage read slightly higher than normal temp..

This is what has happened at this point, plus I read on the rave CD, that I can test the thermostat. I can do this by removing the T-stat, and putting it in a bucket of water, heat it up and observe the temp, and record the temp at which the thermostat opens, and if it is out of spec, (88 degrees Celsius), the T-stat is bad.

Also that cap on the expansion tank, it has two circular things on it, what does this do? Does this vent it to the outside air? Cause I notice that there isn't a normal vent or hose that opens the tank to the outside air. What should be done here?

[Greg M]

Sounds like you just had an air pocket in the system that finally passed. Check to see if both rad hoses are hot along the entire length of the hose too. Did you do any cooling system work before all this happened?

[RageRover]

This all happened yseterday after I did a coolant flush, the flush was done because the coolant in there was bad enough, no good protection with the tester device. Plus she started to overheat a little bit the days before, shortly after coming off the freeway, and coming to a stop, she would heat up then after rolling again, she cooled down to normal, then later yesterday, she did the abnormal overheating thing, then today, nothing happened, just normal.

[Greg M]

Yeah, if it happened after you flushed the coolant you had a air lock.

[RageRover]

I hope so, I don't feel like breaking down on the freeway on the way out to CO, cause I didn't replace something. But it would make sense that a quick air pocket was trapped in the block and got free.

[Paul Grant]

This may not have anything to do with your problem but... Just last night Terry S., AAXD, Murphy and I were sharing pints and talking about high engine temperatures. Murphy and Terry S., two guys that own more than their fair share of British cars, were commenting on how common a failed vacuum advance is as a cause. So, you might want to check the vacuum advance on your truck.

[Greg M]

Originally Posted by Paul Grant

This may not have anything to do with your problem but... Just last night Terry S., AAXD, Murphy and I were sharing pints and talking about high engine temperatures. Murphy and Terry S., two guys that own more than their fair share of British cars, were commenting on how common a failed vacuum advance is as a cause. So, you might want to check the vacuum advance on your truck.

Really? How would that happen? Too lean a mixture would cause it too, and maybe even too much advance (certainly casue dentonation) but a delayed timing spark?

[RageRover]

That is what I read in my RAVE manual, it read that offset timing can cause minor overheating cause of no vacuum advance.

Good point!! I will check the advance and check, re-check and do it all over again, to make sure the timing is where it needs to be. I have not timed her at all since I've had her since last December. Just need a timing light and I would be set.

[RageRover]

Originally Posted by Greg M

Really? How would that happen? Too lean a mixture would cause it too, but a delayed timing spark?

I am not sure how, but I think it would have something to do with how advanced it could be, cause of possibly too much advance from teh vacuum line, but that wouldn't make sense. I ran my other Probe 2.2L 4 banger a little advanced to get it to run better, it never overheated, but we have V8s, totally different.

The overall rule I was told, advancing the timing too much can make the engine over heat. Too retarded, can possibly cause the same thing, I think, because too much fuel is put in, and when burned, burns too much, backfires, and overheats. I think this is what I was told, but i am not totally sure. Someone can correct me if needed, to clarify.

[Paul Grant]

It's a matter of being retarded. Sorry, I couldn't resist.

[RageRover]

LMAO, yeah I knew someone was gonna say something like that.