Idle Overheating

[Glenn B.]

Re: Idle Overheating

I believe I've had the current cooling condition for many years. I have always just tried to avoid prolonged idle. What I did not appreciate until very recently was that may temp gauge is actually reading LOW by about 15 deg, when most read high. Its too easy to get stuck in bad traffic here, and pushing up to 260 is just too high for my liking.

The OEM rad had a whole new core put in when rebuilt. Its hard for me to compare before/after rad rebuild - as I also had the cluster and gauges done at similar time.

I ordered a Robertshaw 330-180 thermostat and a Hayden 2711 fan clutch last night. The Hayden is cheap - if it helps - I will get my OEM Eaton rebuilt. I have replaced the fan to correct, but have never touched the clutch.

[Mike T.]

Re: Idle Overheating

Glenn - So far, you've had good answers to all the questions posed. With your comment about the existing clutch fan stopping or slowing down at only a half revolution after trying to spin it, I'd be surprised if a new unit would do any better. So, maybe it's either something we haven't touched on yet. Do you happen to have access to a pressure tester? Curious if the cooling system and cap hold pressure.

[Glenn B.]

Re: Idle Overheating

I hate just throwing parts at a problem - but the high flow stat and aftermarket clutch are pretty cheap and good spares. I can then at least eliminate these from my suspect list.

I could also clearly see with my timing light that even when hot - the fan was running noticeably slower than the pulley.

Hope to get them installed and report back next week.

[Patrick H.]

Re: Idle Overheating

See Duke's reply in post #7.

I had a long reply typed out in support and relating my own experience, but it got lost.
Read it 3 times, then follow his directions.

Fix the timing before wasting time and money elsewhere.

Patrick

[John H.]

Re: Idle Overheating

Your suggestion to use the timing strobe on the fan is good one , I had the same idea myself this aft. I can say it is clearly running slower than the crank at idle.

Is there a simple and reversible way to lock up the fan clutch?

Glenn -

No, there isn't - it was never designed to lock up fully; it will probably never exceed 80% of crankshaft rpm at its engagement extreme.

[Glenn B.]

Re: Idle Overheating

Patrick - read my post 11. I don't have an idle timing problem.

Also found last night that my dist cap contacts were badly pitted and replaced the cap - runs smoother. I also checked the dist advance curve today (up to 3,000 RPM) and it is within a couple degrees of factory spec.

Anyhow - progress... I found the Henry Molatch article. I removed my clutch (which is CK service replacement) and tightened the spring. I now get 17 or more degrees diff between rad inlet and out, a gain of about 5 degrees. Car ran 15 min at idle and went from 185 to 245 at thermostat (with IR gun)

Maybe I should declare victory and move on..

Going to still install the robertshaw and see what that does

[Patrick H.]

Re: Idle Overheating

Patrick - read my post 11.

I did, even before I replied.
That doesn't mean I agree with your assessment, though.

Let us know what seems to work.

[Glenn B.]

Re: Idle Overheating

An update on my progress... I replaced the STANT 160 thermostat with a high flow Robertshaw 180, and I replaced the OEM Easton fan clutch with a Hayden 2711 service replacement. I could not perceive a difference in the amount of fan spin (hot or cold) with the new clutch. Regardless - I am reasonably happy with todays result. In 15 min at idle I went from 185 to 230 degree (with IR gun at Tstat housing), and the thermostat housing to lower rad range is 17 to 20 degree range which I believe very normal. I can bring the idle temp down by revving the engine

I am going to put the Easton back in (re-measure) then change my coolant - I believe I am now in the range of what is considered "normal"

Thanks for the input and advice.

[Joe C.]

Re: Idle Overheating

An update on my progress... I replaced the STANT 160 thermostat with a high flow Robertshaw 180, and I replaced the OEM Easton fan clutch with a Hayden 2711 service replacement. I could not perceive a difference in the amount of fan spin (hot or cold) with the new clutch. Regardless - I am reasonably happy with todays result. In 15 min at idle I went from 185 to 230 degree (with IR gun at Tstat housing), and the thermostat housing to lower rad range is 17 to 20 degree range which I believe very normal. I can bring the idle temp down by revving the engine

I am going to put the Easton back in (re-measure) then change my coolant - I believe I am now in the range of what is considered "normal"

Thanks for the input and advice.

Seal any gaps between the radiator and the fan shroud, including the bottom seam. Use black foam strips for this and you can buy pipe insulation and cut the strips from it. Wedge in place with a putty knife or wide screwdriver. Once you do that you should be able to idle forever without any temp rise.

Easily removed for judging.