Overheating...AGAIN!

[pwilliam]

I'll check the radiator tubes tonight. I checked last night and got temp fluctuations of about 10 to 30 degrees in some cases, however it was breezy out and the IR Thermometer seems to pick up that type of interference.

I did check the bottom of the radiator near the fan's thermal sensor last night when it was running. It read 202 and the sensor read 193. If it read 193 on the outside, I imagine the contact surface on the inside of the radiator was even hotter. A few degrees higher and the fan would kick on.

I've looked at a lot of previous threads, reading the fan should kick on right at 190 and bring the temp back down, but I have heard sometimes the temp can rise up to 210 with some cars before the fan comes on and brings it down to 190. What is the ideal temp for the fan to kick on? Again, my fan only kicks on for a few seconds and then off, another minute or two and then back on for a few seconds when the car is about 210.

I hot wired the fan to run constantly and the temp stayed right below 190. I thought with the fan running for 10 mins while the car was idling it would get lower to maybe 180 or so, but that never happened in the 10 mins I had it going.

[So Cal Mark]

the fan should come on at 195, then cycle off at 185. The radiator shouldn't fluctuate 30 degrees between tubes, that indicates restricted tubes

[majicwrench]

Anything that restricts flow--pluggedd rad, impeller issues, t stat etc--- can cause fan to cycle quickly.
There's no reason the fan running constantly should reduce the temp to 180 unless you have an improper t stat.
IR gun can be interesting to get accurate temps depending on what it is reflecting off of.

I would disagree about plugged convertors causing overheating, but that ain't the point.
Keith

[So Cal Mark]

wow, do you try to contradict every post of mine? I see half a dozen of these cars every day. The fan should cycle off at 185. Temperature drop across a properly flowing radiator will only be 10-15 degrees.
Engines like a constant temp, not wildly fluctuating temperatures.
Obviously you haven't dealt with plugged cats much. A plugged cat will turn an exhaust manifold cherry red and melt the tips off the spark plugs. But along with that is an extreme loss of power, so the car is really not driveable, although I've seen owners attempt it.

[majicwrench]

Mark,
Didn't feel I was being contrary..was agreeing that "anything that restricts flow...."

And was letting OP know that if he was expecting temp to drop to 180 he may not see that with properly operating t stat.

And I don't wish to debate convertor/overheat, unless you do. I see em all the time, I do this for a living too.
Keith

[4uall]

Losing focus.................stay on target

http://www.youtube.com/watch?v=NnP5iDKwuwk

[pwilliam]

Trying, haha! Tested the radiator with the IR gun, pretty consistant all the way across, deviations of about 5 to 10 degrees. No breeze out last night, so it is a more accurate reading. I'm feeling pretty good about the radiator, tstat, sensor....head gasket must be the next stop! Not again!

I have read in older posts, some people will not put the gasket on without the guides in place. Last time when putting the gasket on, it appeared my guides had slid down into the black and did not want to come back up. Does anyone know where I can purchase these guides, or have a set I can purchase from them?

Didnt see any on auto-ricambi, vick or IAP. This will be my fourth time removing the head, dont ever want to have to to do it again for a long while. I am just looking for anything that will help ensure the process. Last time when putting the head gasket on, all of the bolts threaded through nicely so I assumed it was all good, but perhaps not so in the end. A straight edge was also put agains the head to check for straightness, this was done down the sides over the bolt holes, diagonally both ways, and on each end. No daylight was peeking through. Maybe I just have a cracked head.

[majicwrench]

THe guides certainly have to be in place, and be sticking up enough that they engage the gasket and head.

IF you do the hd gskt again, one thing a lot of folks miss, the hd bolt holes are blind, closed at the end, anything like coolant or oil in there and you will not be able to tighten bolt properly. Blow out bolt holes or at least stick paper towel in em to get all liquid out.
Certainly possible head cracked, but in my exp that is not likely.

I'm not gonna tell what is or isn't bad here, been all over the place with this. I will say that if with fan running temp stays fine, that is really all the system has to do. Did you take it on road with fan running??
Keith

[pwilliam]

Hey Keith,

Took it on the road without the fan hot wired, but still hooked up. I drove it for maybe a mile or so. When I got back and let the car idle the temp climbed to 240 without the fan engaging. Possibly a result of more air being pumped into the system? Just confused as to why the temp climbs so high but when I have to put coolant in the system after the car cools down, it is only such a small amount, a tablespoon, maybe just a bit more.

I realize when the car cools it will suck coolant back in through the radiator cap. The last time when my head gasket blew, I would have to put a significant amount of coolant back into the system though.

One thing that struck me is that perhaps if not all of the oil was drained fromt the head, prior to reinstalling it, some could have leaked onto the gasket before it was tightened...same with coolant too I suppose. I thought maybe this would heat and burn off if such a thing happened but maybe not. Any thoughts if a few drops of oil or coolant on the gasket could cause an overheating issue?

[blazingspider]

I chased a problem like this on my car one time. Car would run fine for awhile maybe even up to a week or so, then it would begin to overheat. I would find air in the system and would have to fill it with a bit of coolant and then burp it again. After checking all of the obvious culprits it turned out to be my heater control valve.

It had a very, very tiny leak. So small that you wouldn't even see any coolant on the passenger floor of the car but after awhile it would suck enough air into the system eventually to create my overheating problem. Not saying this is your issue but to test you could bypass the heater core by running the hose from the back of the head over to the return pipe.

FYI...I have also seen flaky switches for the fan. I've tested mine by placing them in a pot of water with a thermometer and an ohm meter hooked up to the spade terminals (water level below spade terminals of course). Had one once that would close the circuit at all different temps from 185 to 210. It wasn't consistent at all.

Good luck and let us know how it all turns out.

[pwilliam]

Thanks for the suggestion! On Sunday I did find traces of coolant at the heater valve, by the bolts that attach it to the short pipe. Tightened it up and didn't seem to find any more coolant. I should mention I annealed the original pipe to accommodate the new heater valve I installed. I thought it could have been possible I damaged it but it doesnt seem so. As you noted you had a very small leak so anything is possible right?...or I just did a shit job installing the heater valve...like I said anything is possible! It had been running fine for weeks after in installed but it could have failed at any point. Same as you, no coolant on the carpet, not even down the heater valve. Just moister by the bolts. Can't wait to get home and try the bypass! Wish me luck! I'll be sure to report back, hopefully with a fully operational spider!

[majicwrench]

Not doubting anyones experiences, but it would be a stretch to think that enough air could get sucked in thru the heater valve tro cause an issue. Coolant is under 13lb pressure, and will leak out whatever hole you have. So yes, if you have a coolant leak, you could possibly suck air into the system when the system cools down. If you don't have a coolant leak, realisticly is not sucking air back into system, or at least not enough to make a diff.

P, why would you be suprised that temp would rise to 240 after drive and let sit idling WITHOUT THE FAN RUNNING?? Yes it is gonna run hot without the fan running. We are going in circles a bit, if radiator is getting hot, fan should run. Is radiator getting hot?? If so, why is fan not running?? If you hotwire fan, can it control the temp?? If so, you NEED TO GET THE FAN TO RUN PROPERLY.
Keith

[pwilliam]

Hey Keith,

My surprise was that the fan would not come on at 240, not that the temp actually got that high. Sorry for not clarifying. I find it strange that the fan would kick on around 210ish, i would take the car for a drive and the temp would rise to 240 and no fan at all. As noted it is not possible for the air to get sucked back in while the system is under pressure, so its likely that the heater valve issue might not be responsible.

In regards to air getting sucked back in and causing problems, it seems that their are quite a few threads on the forum related to people having air in the coolant and running hot due to a leak located at the heater pipe to water pump connection. Their overheating/air in the system problems were resolved after correcting this issue.

At this point I cant afford to discount any suggestion. I think your head gasket suggestion is valid, but as I dont have the opportunity to take the car to a shop and get this verified until friday or the weekend, I'm trying other things in the meantime. I'll give the bypass a go and report back tomorrow. Thanks for hanging in there with me, folks!

[majicwrench]

LIke I said, am not doubting anyones experiences about air being sucked thru heater valve and causing issues. People believe in Bigfoot and UFO's too and that's fine with me.

P, with all due respect, your first paragraph does not make sense to me. Your suprised the fan would not come on at 240, but the temp never actually got that high?

And without reading all the old posts, I don't think I ever said it was head gasket. I may have said something to the effect that the only way for air to get into system is hd gasket/head.

Anyway, best of luck, let us know what happens!
Sincerely,
keith

[pwilliam]

I am surprised the fan did not come on at 240. I am not surprised that the temp got to 240. Excuse my grammar. Will keep you updated and going to run it with the fan running constantly as you have suggested.