[Shelby1]

Let's see you have replaced every thing in the cooling system.....The only thing(s) left is the block and heads, if the block's cooling passage's are half full of sludge you will get the conditions you are having because only half of the cly's have coolant around them and the other half is building heat tru the sludge and is super heating the coolent. With the sludge there the clys can't be cooled within the range of the thermostat.as was stated in a earlier post open up the block drain(s). If you get brown sludge then the block will need to be flushed and the back flush that is done by some shops won't cut it, You will need to take it to a radiator shop and have it pressure flushed.And if it was me I think I would pull the block drains out of the block so I could get a better look at the bottom of the cooling passage's and if all else fails as a last resort the freeze plugs .If this motor has not been rebuilt then it has had 40 years to build up sludge in the block so there is a good chance it's there.A few years back a friend brought a 283 to me to rebuild for him ,when we knocked the freeze plugs out the sludge was higher than the plugs,and the man that he got the motor from said that it had been running hot.
Also both 68's that I owned had 180 degree thermostats and nether ever ran over 200 even with A/C.

Good Luck and post back and let us know what you find
Kenny

[Deuce]

Originally Posted by cmk59

I ran with the OE setup for 3 years before the old girl developed her 'issues.'

I went with the dual electrics because it was a matter of economics. The fan AND clutch were shot (fan coming apart at the rivets), and it was going to cost as much to replace them as to get the two electrics (on sale at that time).

I rest my case for original GM stuff ...

Worked for three years ... clutch fans do wear out. Hayden makes replacements ... original GM units are on eBay ( new ) all the time ...



This one is on now for 90 dollars @ Buy it now price ...



Junk yards are full of fans ...

College degrees do not fix cars. My wife has two ( one a Masters ) and she cannot work on her new Cadillac Deville either ...

You supervised a 225 million dollar motor pool and you take you cars to a mechanic ??
______________________________________________





I do practice what I suggest ... both of my 430 HP 32 Fords use a clutch fan and a shroud ... and run @ 180 to 190 even here in the HOT, HUMID South

_____________________________________________

Please disregard my advice ... I was just trying to HELP you get your car running on temperature ... Apparently you or your mechanic is enjoying this

[cmk59]

Originally Posted by Holder350

you say you ran the stock setup for 3 years without trouble?
Seems strange that this happened all of a sudden.
I hate to sound stupid but are you 100% that the gauge is correct?
Is it puking water out of the overflow?
.....the original Tstat had a small hole in it to bypass water by the stat, Hondas use a bleeder screw below the water neck. If theres no water on the stat it will not open.
You know more about what has and hasn't been done, I'm just grasping at straws here to try and give some ideas!
Also... I dont know how your mechanic flushes the system out......but I always take the upper hose of the rad, start it up and let it warm up, all the while keeping the radiator full. (thru the upper hose inlet)
when the engine temp hits the Tstats temp water will start POURING out of the upper hose. I then let it run till it the water coming out of the upper hose is clear.....
This lets you know that the entire system is clean, plus because the water must go thru the rad, engine and the Tstat.....you know if its flowing adequately.

Well, it hasn't really happened all of a sudden, but has been an on-and-off thing...the idiot light was held largely at fault, as there was no replicable set of conditions where the light would show overheating, even in winter! I chalked it up to a bad sending unit when a guy with an IR meter measured the temp at 10 points around my engine block and came up with temps between 179 and 182. I figured the sending unit was the culprit. Then I started having real problems in year 4....

As to the gauge, who knows how correct they are from the factory? I bought a name-brand gauge (Auto Meter), that was the best I could do...nothing to measure its performance against...but that's a very good, valid point!

Yes, when it overtemps, the coolant comes puking back out the overflow tank's vent. I installed the overflow tank when I bought the car and saw it didn't have one...a fairly smart move on my part, I thought...

Y'know, I've seen where people recommended drilling an 1/16" hole in the side of the t'stat (flange) to enhance cooling, but had never considered it an issue before...and the stats I've bought have never had such a feature. Things that make you go...well, you know.

I don't mind grasping at straws, either...it's people that say you did something wrong when you didn't that is irritating. You're fine!

As to flushing the system, when I did my own (before the disability limited my ability to work on my own cars), I removed the t'stat, reinstalled the housing and then did exactly what you described, occasionally using a flushing agent if the radiator had gunk in it. We're definitely of like minds there! AS to how HE did it, well, that's anyone's guess...as I said, not being able to work on 'em myself anymore, you take your life (er, car) into your own hands putting your faith in someone else...kinda like when I paid a guy to put new suspension pieces I'd bought from Impala Bob's on my Impala, and he only installed 1/2 of them, saying the rest of the bushings, etc were fine...but that wasn't what I asked and paid him to do, and he refused to finish the job to my satisfaction.

We're still in litigation over that little deal, but he has more money than I do.

Chuck

[cmk59]

Originally Posted by Shelby1

Let's see you have replaced every thing in the cooling system.....The only thing(s) left is the block and heads, if the block's cooling passage's are half full of sludge you will get the conditions you are having because only half of the cly's have coolant around them and the other half is building heat tru the sludge and is super heating the coolent. With the sludge there the clys can't be cooled within the range of the thermostat.as was stated in a earlier post open up the block drain(s). If you get brown sludge then the block will need to be flushed and the back flush that is done by some shops won't cut it, You will need to take it to a radiator shop and have it pressure flushed.And if it was me I think I would pull the block drains out of the block so I could get a better look at the bottom of the cooling passage's and if all else fails as a last resort the freeze plugs .If this motor has not been rebuilt then it has had 40 years to build up sludge in the block so there is a good chance it's there.A few years back a friend brought a 283 to me to rebuild for him ,when we knocked the freeze plugs out the sludge was higher than the plugs,and the man that he got the motor from said that it had been running hot.
Also both 68's that I owned had 180 degree thermostats and nether ever ran over 200 even with A/C.

Good Luck and post back and let us know what you find
Kenny

Kenny, you (re) present an earlier suggestion, but with the best and most cogent argument for doing it yet, and one that makes eminent sense, given what I've already been through. Bless you, and I will take your comments to my new mechanic and insist on such a power flush...I was leaning toward that, but now I'm convinced!!! Pls contact me off forum at cmk59@yahoo.com, and I'll keep you up-to-date..I can't always be on the forums!

Chuck

[Deuce]

Originally Posted by cmk59

(before the disability limited my ability to work on my own cars)
Chuck

Sorry to hear about your disability ...
I had a heart attack a few years back and was down for about 3 months before I could start back towards regaining my strength and mobility. 5 bypasses will do that to you.

I had a 68 Chevrolet and it ran 190 ot 200 with the A/C on. I had added Stewart Warner temperature gauge to the car. We got 68 Impala NEW ... so I never really looked at the range on the thermostat.

Overheating issues can be very frustrating.
Hopefully you will prevail.

Deuce ...

[cmk59]

Originally Posted by Deuce

Sorry to hear about your disability ...
I had a heart attack a few years back and was down for about 3 months before I could start back towards regaining my strength and mobility. 5 bypasses will do that to you.

I had a 68 Chevrolet and it ran 190 ot 200 with the A/C on. I had added Stewart Warner temperature gauge to the car. We got 68 Impala NEW ... so I never really looked at the range on the thermostat.

Overheating issues can be very frustrating.
Hopefully you will prevail.

Deuce ...

I appreciate your help, Deuce, I truly do. The ideal I'm striving for is what you just described with your '68...no more, no less. When you're in the shape I'm in (and the drugs don't help much in high humidity, save to make you feel worse!), a comfy car with a good AC is worth its weight (and then some) in gold...or gas!

I'm dealing with ruptured discs, spinal stenosis, lymphedema and early-stage MS. My heart, after a week of tests, is ok, though I have a funky valve they want to keep tabs on. Fun, huh? Still, my 'baby', my Impala is one of my great joys next to my wife...sux that I have to endure this at just 48 after serving most of my life in the USAF, but that's life, and you play the cards you're dealt.

Kenny has a good idea, and with the suggestion the gauge may indeed be in error, I'm going to have it checked against a different/better(?) one and see what happens. Still, it's hard to argue with puking coolant and the temp showing hot, y'know? A more accurate gauge would definitely lower the angst, though!

Thanks again for the kindness and thoughts. I'll keep everyone up to date as I find out more.

Chuck

[malc]

Water temp gauge accuracy, how to check if it´s working right or not.
What make of gauge do you have in the Imp ?

[carsavvycook]

Chuck, Thank you for your service in the USAF.

[66GMC]

My $0.02, and don't intend to offend anyone else with it:

I have never been a fan of "diagnose it over the phone" (or the internet) or of "throw parts at it until it runs" either. Strange as that may sound ... coming from a partsman. (Ford / NAPA mostly)

A power flush certainly wouldn't hurt a darn thing.
Taking the rad out of the car, and having it cleaned in a radiator shop's caustic tank, checked for leaks, fins straightened and repainted also would be a good thing to do.


Having now covered the MAINTENANCE ...

There ARE tests that can be done.
A pressure test has been mentioned.
There is a hydrocarbons test of the coolant that would tell you if there was a head gasket or block problem.

Quite often there is a spring inserted into the radiator hose(s) that prevents the hose from being sucked flat. I would think this would be a mandatory requirement for a hi-volume water pump.

Does the car cool normally at idle, and heat up only under load?
Assuming that it's an automatic, is it in good shape? Are you running a stall converter? Is there a tranny cooler? Does the tranny fluid smell burnt?

Please tell us that you ARE running ordinary green GLYCOL antifreeze mixed 50/50 with water ... and that you have never switched or topped up with a non-standard coolant like "Long-Life" or "DexCool" which usually has a pink or orange hue to it. The two types are definitely NOT compatible, and will cause gelling and all sorts of problems.

[paulo1]

After all that has been said and tried I say it can only be combustion heat entering the cooling system.Please try a cylinder leak down test.

[bluesman2333]

One thing you can for free is go to an auto parts store and rent a cooling system pressure tester. you pony up the cost of the tester and they refund it when you return it. This will eliminate the possibility of it overheating by not pressurizing.

[Holder350]

I would also suggest after all this to take it to either another mechanic or some type of speed shop.....(or if you happen to drive by someones house who has a drag car, dirt track racer, or hot rod) and have them check and recheck the timing.

80% of SBC cooling problems are timing related.


Also.....my heart goes out to you about your health. I cant imagine not being able to work on my cars.

Late last year I was in the hospital for 8 days while the tried to find what was wrong with me.....in that time I had lost all mobility, I couldn't move my legs and could only barely move my arms.

I'm 20 and was scared to death that I had MS.

They finally diagnosed me with Gillan Barre Syndrome. There is no treatment for it except to let it run its course.....It took me 2 months to be able to walk again and another month to get my strength back.

I have a new found gratefulness for my health

[bluesman2333]

Speaking of timing, if everything checks out, you could try to retard the timing 3 degrees to see if the problem gets better. It won't repair the problem, but possibly will allow you to drive the car for a while until you get a repair plan in place.

[Shelby1]

I have never been a fan of "diagnose it over the phone" (or the internet) or of "throw parts at it until it runs" either. Strange as that may sound ... coming from a partsman. (Ford / NAPA mostly)
I agree with you 100% 66GMC,but in this case I believe the situation warrant's any thing that we (hotrodders on this site)can come up with.That being said Paulo1 & bluesman 2332 stated to pressure check this system,if it has a blown head gasket it should not hold pressure if every thing else is right,a compression check should show a blown gasket ( cyl next to each other showing low or same pressure's)but the thing that I remember most about a problem like this what the old man that I use to work with would do . If he thought that a motor had a blown head gasket/cracked head or possible cracked block was to pull the radiator cap and see if there was bubbles coming up tru the coolant. He would say "If it's leaking compression it has to go tru the water there is no other place for it to go" which makes sense given the pressure difference between the cly's and the cooling system. So if it does have a blown gasket there should be bubbles in the coolant seen at the rad cap opening. I remember one that was in the shop that was so bad , at idle it would blow big bubbles out the neck and if you reved it up it would blow a large column of water out the neck.

Later
Kenny

[T-bucket23]

just a few items

Presure in the system has NOTHING to do with its ability to cool, it controls the boiling point, every LB = 3 degrees increase. So a 15LB cap will add 45 degrees to the normal boiling point of your coolant.

A flush is usless if you dont take out the block drains or knock out a freeze plug. You can run water through it frontwards backward or sideways, the crap that builds up in the blocks lower passages will still be there. We have proven this a few times by pulling a freeze plug after a "power flush" and the crap is still there.

You issue sounds like you have a lack of air flow or a plugged radiator, both have the same effect on the cooling system.

As far as thermostat size a 180 or 195 would be fine but its not you issue as with a 160 it is boiling over so a 180 or 195 is not going to make any difference. Many chevy 350 applications have used a 195, you need a new parts guy if he cant find one for you.

Get the original type clutch fan and shreoud and I think your issue will go away.

Cooling systems are not magical.


Chet