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  #61 (permalink)  
Old 07-02-2008, 01:39 PM
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In my 40 plus years of messing with SBC's and BBC's ... I have NEVER had a issue with a engine cooling system clogging up ... if the engine has not been sitting unused for a few years. I have had radiators plug up ... even with regular use.

I wish you were closer ... I am sure I could fix the problem.

I would check for vacuum leaks ... at the distributor advance ... the line to the advance from the carb. Then I would check to see if the carb was sending a vacuum signal ... Then see if there was a vacuum leak under the carb. I would then remove the radiator and have it cleaned. NEW hoses ... with the wire in the lower hose. Fresh coolant.

If the timing is correct ... and the radiator is clean ... and you still had issues ... Then it could be the block clogged ...

But I doubt it would still overheat with that work done.

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  #62 (permalink)  
Old 07-02-2008, 02:13 PM
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@Shelby1, a bad head or gasket is only one possible place you can lose coolant. Doing a pressure test pretty well covers them all.

@T-bucket23, you are wrong. Pressure has EVERYTHING to do with a closed system being able to cool. I have personal experience with this on my own vehicles and customers vehicles. You are right on stating a flush isn't helpful unless you pull the freeze plugs or the drain plugs. That's why I suggested the OP do it.

@Deuce, I have seen blocks plugged up to varying degrees, one particular one I remember was about filled up. I assume it was stop leak from trying to fix a bad water pump.

At any rate, I would like to show up on his door step too and fix it. On one particularly bad one, I even taped thermometers to the upper and lower rad hoses to check for temp differential because I was running out of ideas.
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  #63 (permalink)  
Old 07-02-2008, 02:58 PM
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Quote:
Originally Posted by bluesman2333

@T-bucket23, you are wrong. Pressure has EVERYTHING to do with a closed system being able to cool. I have personal experience with this on my own vehicles and customers vehicles. You are right on stating a flush isn't helpful unless you pull the freeze plugs or the drain plugs. That's why I suggested the OP do it.
Actually I am correct the pressure is to raise the boiling point and has nothing to do with cooling. It is to keep the coolant from boiling at the normal boiling point. Once coolant starts to boil it can no longer cool and it pukes out. Dont get me wrong, it is important to have pressure but it does not assist in cooling at all. Just keeps the coolant in the system
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  #64 (permalink)  
Old 07-02-2008, 03:09 PM
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Quote:
Originally Posted by bluesman2333
I have seen blocks plugged up to varying degrees, one particular one I remember was about filled up. I assume it was stop leak from trying to fix a bad water pump.

I also have never seen a block plugged up......I have however seen them FILLED up.....block fill has been used over the years to over bore a motor to that last little bit.
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  #65 (permalink)  
Old 07-02-2008, 05:26 PM
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.02....

Quote:
Originally Posted by 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.

Brand new radiator...still gleams inside, in fact. Hydrocarbons test might work, but hose is fine..has the coil inside...in fact, both upper and lower do in this instance - neither has gone flat or close to it. As to temp, it doesn't matter much what regime I'm in. The temp goes up, and stays there. I use only ethylene glycol antifreeze, mixed 60/40 or 50/50; have lost one engine to the orange crap, and will never use it again.

As to the tranny, it's a box-stock TH400, with only fluid and filter changes to its name so far. I added a 3/4 ton truck auxiliary cooler to it, and the same size cooler for the engine oil, btw. Fluid has, and does, still smell and look fine. Clearish-red, w/no browning/scorching or burnt-almond smell.

So far, so good, at least there.

Chuck
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  #66 (permalink)  
Old 07-02-2008, 05:35 PM
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?????????

Quote:
Originally Posted by Deuce
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

Trust me, Deuce... no one is enjoying this, least of all me. AND while college degrees do not fix cars, people do, and the worst thing anyone can be is uneducated in an area where they're spending money. As to sending my car to a mechanic, where do I send it...a witch doctor? As it is, I've JUST spent all day today in the hospital yet again, only to find out I now also have atrial fibrillation. I'm on coumadin, Avellox, nitro glycerin and amylodipine until Aug 5, when they'll decide whether they're going to shock my heart back into rhythm or not.

Working on my own car, as I've already said (and even if I were better at it than I am..PM is my best quality), is now completely out of the question. I just hope that whomever works on my car now is more thorough and trustworthy than their predecessors.

And to the person who thanked me for serving, bless you. That kind of thing out of the clear blue means a lot to all of us.

Chuck
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  #67 (permalink)  
Old 07-02-2008, 05:37 PM
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Gauge

Quote:
Originally Posted by malc
Water temp gauge accuracy, how to check if itīs working right or not.
What make of gauge do you have in the Imp ?
Right now, I have no way of checking anything with my heart going wonky, but I appreciate the suggestion..I'll have to pass it on to whomever works on the car. As to the gauge, it's an Auto Meter brand, about mid-line...I paid about $45 for it. Just didn't have the coin at the time for a better one, and no one was about to install an in-block sensor for me, so I was kinda limited, unfortunately.

Chuck
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  #68 (permalink)  
Old 07-02-2008, 05:49 PM
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Grateful for my health..

Quote:
Originally Posted by 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
Holder, I hear you. I'm only 48, and I actually meant to say in an earlier post that they'd diagnosed Muscular Dystrophy, not MS, not that there's a HUGE difference...but today, they also diagnosed Atrial Fibrillation. (I posted on it in a later post here answering someone else's question, so I won't re-post here.) You DO take things for granted sometimes, and I no longer do. I hope you make a rapid recovery from you Guiilain Barre Syndrome, and are never bothered by it again...it's a scary thing to have your health suddenly taken away from you.

Between the hydrocarbon test, timing check and the block drain/flush, I'm hoping all will be ok. Besides, it takes my mind off of ... as Gene Simmons would say ... ME.

Chuck
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  #69 (permalink)  
Old 07-02-2008, 07:06 PM
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Just before I had to Register for the Draft they canceled it. At that time I had an entry level job as a mechanic, you know oil changes, water pumps, etc., whatever the senior mechanic's did not want to do, and I loved it. After hearing from my older brother about how they treated him in Boot Camp, I knew that was not for me. That mentality has been my "driving force" for years, in opening my own shop. I have worked for "drill instructor" type shop owners along the way.

I have the up-most respect for anyone who has, or, is serving, in the US Military, and I'll repeat Thank For Serving in the USAF.

Now back to the original thread question. There have been some very good posts for what you need to have done. Compression test OK, Leak down maybe, Cooling system pressure test good idea. Retarding the timing marginal.

To be absolutely sure you do not have a head gasket problem, drive it by a Smog shop, and ask them to check for exhaust gases in the cooling system recovery tank, or radiator. This is the fastest, and most efficient way to test for it. Trust me on this test procedure. I found a 45 second "window" just before the thermostat opened that showed high HC'S, on a 1988 Mercury Tracer. My combustion leak tester, and the spark plugs, along with a compression test, and a cooling system pressure test did not show anything. It too, was pushing the coolant out of the reservoir. After it became low enough on coolant the car would overheat. It took a magnifying glass to finally find a hair line crack starting in the cylinder head, from the water jacket, but, not past totally past the the combustion ring on the head gasket.

Now a suggestion. Go to kudzu.com and do a search for a auto repair shop in your area. Look for a shop with good "customer recommendations". In other words, find a new "mechanic". I too wish I was your neighbor.

Stephen
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  #70 (permalink)  
Old 07-02-2008, 07:21 PM
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I've had similar high speed overheating problems with my '75 GMC pickup, and have not yet figured out the cause. I could leave the truck idling in my driveway for hours and it would not overheat, but if I drive it at 70 mph the temp will slowly climb until it hits about 230 and I decide to pull over and drive slower (about 45 mph) until it cools down. Thermostat temp does not seem to matter, since I've tried both a 195 and a 180 and did not see a change in the overheating problem.

My truck has a GMPP 290 HP 350 with Edelbrock carb and manifold, but the rest of the cooling system is stock. Nearly all of the cooling system parts were replaced when I put the new engine in a couple of years ago, with some minor changes (Mr. Gasket high flow thermostat and Hayden HD fan clutch). The OEM shroud and steel fan are still there and the heater is fully functional. I'm using a GMPP HEI distributor with 12 degrees initial, about another 20 from mechanical, and about 18 more from the vacuum advance (using the manifold vacuum port).

One recent discovery was that the steel vacuum line to the TH350 had a hole worn in it from resting across the top, rear corner of the exhaust manifold. I don't know if this vacuum leak could be part of the high speed overheating problem. I haven't had the truck out on the highway to test it since I found the bad steel line and replaced it.

Bruce
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  #71 (permalink)  
Old 07-02-2008, 07:35 PM
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Toooooooooooooo Hot

I have built many high horsepower rods and muscle cars. The key is having a shroud. If possible I always use a puller fan and a shroud is the key. The shroud makes the air get pulled from all corners of the radiator, essential to cooling a hot running engine. If you are running 210 and the temperature climbs while sitting in traffic, a shroud will keep your temp. down. Good Luck, Tom.
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  #72 (permalink)  
Old 07-02-2008, 08:24 PM
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Quote:
Originally Posted by 75gmck25
I've had similar high speed overheating problems with my '75 GMC pickup, and have not yet figured out the cause. I could leave the truck idling in my driveway for hours and it would not overheat, but if I drive it at 70 mph the temp will slowly climb until it hits about 230 and I decide to pull over and drive slower (about 45 mph) until it cools down. Thermostat temp does not seem to matter, since I've tried both a 195 and a 180 and did not see a change in the overheating problem.

My truck has a GMPP 290 HP 350 with Edelbrock carb and manifold, but the rest of the cooling system is stock. Nearly all of the cooling system parts were replaced when I put the new engine in a couple of years ago, with some minor changes (Mr. Gasket high flow thermostat and Hayden HD fan clutch). The OEM shroud and steel fan are still there and the heater is fully functional. I'm using a GMPP HEI distributor with 12 degrees initial, about another 20 from mechanical, and about 18 more from the vacuum advance (using the manifold vacuum port).

One recent discovery was that the steel vacuum line to the TH350 had a hole worn in it from resting across the top, rear corner of the exhaust manifold. I don't know if this vacuum leak could be part of the high speed overheating problem. I haven't had the truck out on the highway to test it since I found the bad steel line and replaced it.

Bruce
This sounds strongly like a case of "87 octane blues". I have been asked to check timing, make carb. adjustments, etc., on many 250-290 HP vehicles lately. Every last one of them have been complaining of "high heat" on the freeway. With the cost of fuel now, they are running regular, when they need to be running mid-grade. JMO
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  #73 (permalink)  
Old 07-02-2008, 08:49 PM
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Thanks again!

Quote:
Originally Posted by carsavvycook
Now back to the original thread question. There have been some very good posts for what you need to have done. Compression test OK, Leak down maybe, Cooling system pressure test good idea. Retarding the timing marginal.

To be absolutely sure you do not have a head gasket problem, drive it by a Smog shop, and ask them to check for exhaust gases in the cooling system recovery tank, or radiator. This is the fastest, and most efficient way to test for it. Trust me on this test procedure. I found a 45 second "window" just before the thermostat opened that showed high HC'S, on a 1988 Mercury Tracer. My combustion leak tester, and the spark plugs, along with a compression test, and a cooling system pressure test did not show anything. It too, was pushing the coolant out of the reservoir. After it became low enough on coolant the car would overheat. It took a magnifying glass to finally find a hair line crack starting in the cylinder head, from the water jacket, but, not past totally past the the combustion ring on the head gasket.

Stephen
Again, I appreciate your kind words on my service, Stephen. Most of us who stuck it / stick it out don't do it for the thanks, but that makes it all the nicer to hear.

Dunno if you heard/read it earlier, but I'd put an ad in the local Craigslist offering my '88 Honda Nighthawk in return for repairs on both my cars. I've got mechanics coming out of the concrete, and so I'm hoping to run all the suggestions I've gotten here by whomever seems most honest and knowledgeable. As I've just (today) been released (again) from the VA - where I found out I'm suffering from 'atrial fibrillation' (see Gene Simmons Family Jewels...he had it happen, too), with a heart rate of 196. (It's supposed to be 60 or so.) I say that in the hope and prayer that the 'new' mechanic is both thorough and honest, as I literally can't afford any more problems!

Thx again, Stephen, and feel free to contact me off-forum to go off-topic, so we don't bore/offend anyone!

To those who suggested mid-octane gas, for now I'll try the octane additives for a tank or two, then maybe the mid-grade, but the evidence kinda suggests that might be negligible at best on the overheat issue. Still, I'll discount nothing at this stage.

I'm also actively hunting for a good shroud for my dual 15" Derale fans, if anyone has one they'll trade me or sell me. Derale won't sell me one, as they will only sell'em in kits with the fans already attached. No one else I can find (Be Cool, etc) just sells the shrouds that I can see, and the prices I've seen at Jeg's are, well, unobtainable for me now. This is where I hope that whomever works on my ride will be able to fab one up and / or have one we can satisfactorily adapt.

I'm thinking that between the timing (which I will[I] check, I promise), the hydrocarbon test, the shroud and draining the block completely via the drain taps should answer my issues. I mean, with all you guys have thrown out there at me, there's not much left, is there? We'll see...

Chuck

Last edited by cmk59; 07-02-2008 at 08:57 PM. Reason: Incomplete post
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Old 07-02-2008, 10:17 PM
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Quote:
Originally Posted by cmk59
I mean, with all you guys have thrown out there at me, there's not much left, is there? We'll see...
Its been the best thread I've ever read on cooling issues with a SBC.. I've learnt heaps! Many thanks to all contributors.

Dunc.
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  #75 (permalink)  
Old 07-03-2008, 08:36 AM
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Quote:
Originally Posted by 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.


Cooling systems are not magical.


Chet

Pressure has everything to do with cooling, especially a SBC.
SBC are notorious for nucleate boiling= steam pockets forming next to the combustion chamber. Once steam begins to form overheating gets worse. That is the reason that SBC had the temp gauge at the front of the left head. The LT1 reverse cooling was an attempt to stop it.
System pressure reduces nucleate boiling.
High flow water pump pressure reduces nucleate boiling. A high flow pump can add several pounds of pressure at the chambers.
Evans Coolant (367* boiling point) reduces it.

***********
Post #1 that the gauge hits 290* is wierd. 50/50 coolant can't exceed 257* with a 16# cap.

When the engine is cold, I would remove the radiator cap and squeeze that lower hose to see if it is collapsing. It better have a spring inside it. IF not, make one from coat hanger wrapped around a broom handle.

***********
Thank you to all military personell for serving.

MIA/POW and PH, you are not forgotten. I wasn't there (VN) but I still care.

former cooling system engineer

Last edited by ScoTFrenzel; 07-03-2008 at 08:55 AM.
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