Cooling/Over Heating???

G

GS81VETTE

Member
Here is a run down of the mods then the problem.

New stealth intake, New Holley 750, New MSD HEI Dizzy, Hooker Side Pipe headers. Everything else is stock and has 70,000 miles on the car.



The problem. The car is running a bit hot about 230 degrees and the oil is running at 250 degrees. When she cools down an I open the hood the top radiator hose is collapsed. The over flow resevoir is full to the HOT mark. I open up the radiator cap and you can hear the sucking of the air and the hose filles out. Then it is low on fluid. The systems seems to suck but the fluid in the over flow does not go in. The hose is on tight and not blocked. When hot it will push fluid into the over flow but it will not pull it back in when cool.



OK That is it. I was going to start with the radiator cap but wanted to get your guys thoughts first.



Thanks

:ugeek:
 
IF your oil level is correct and the transmission heat is not the cause of the overheating, then look for leaks in the system, and carefully adjust your valves, get the adjustment wrong and it runs much hotter than ideal. first and make darn sure the ignition timing is correct and the carbs fuel air mix is in the 13:1 range and theres no vacuum leaks\, and your cooling system has no leaks, after you test...
read these

http://www.circletrack.com/enginetech/c ... index.html

viewtopic.php?f=57&t=940

http://garage.grumpysperformance.com/index.php?threads/white-smoke-only-when-cold.1990/#post-5288

http://garage.grumpysperformance.com/index.php?threads/blue-oil-smoke.12198/#post-59193

viewtopic.php?f=70&t=1411

viewtopic.php?f=4&t=1337&hilit=infrared

viewtopic.php?f=57&t=1540&hilit=infrared

if you do all that and it still runs hot,and your basic system itself can handle the thermal loads,its most likely a flow restriction.
ID bet you can CURE the problem if you REPLACE the two main radiator hoses AND install a NEW THERMOSTAT in which YOU drill 8 1/8" holes evenly spaced around the flange perimeter, and carefully flushing the radiator of built up crud and adding new coolant

viewtopic.php?f=57&t=149

if everything's working correctly you might just need a larger aluminum radiator
 
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Hey Grumpy I did see some white smoke at start up the other day. And with the valve adjustment making an imporvment but not getting rid of all the issues with preformace could I be looking at a damaged head or head gasket? The rad hoses are new (1 year old) as well as the water pump. and the thermostate was replaced a month ago. I was going to start with the rad cap and see what that does but I am afraid I am looking at some head or head gasket damage??
 
Yes I was reading that post. I have a rad pressure tester. And I will run a compression test as we talked about. Everything is pointing to head or head gasket damage. I am not going to drive the car till I find out the answer. I was hoping to get some more miles out of her before I had to tear the heads off but I dont want to cause any more damage so I will run the tests and post the results.

Thanks
 
always drop back to the basics!
any time your car starts acting out of character,
you always need to do basic tests on the basic mechanical function, electrical voltage, fuses, and grounds and gasket integrity , before looking for more exotic causes for problems, for those tests a shop manual, an infrared temp gun, an a/f meter, reading spark plugs, a voltage & ohms meter, timing light, and vacuum gauge and and for anyone reading this,use the darn, infrared temp gun, and using your head, rather than swapping components at random, can be used to isolate the cause. I constantly find its the basic stuff that gets over looked, things like just gaping plugs,setting the timing, adjusting carbs,and adjusting the valves, looking for leaks, and verifying pressure, coolant and oil levels, seems to get ignored
irtemp.jpg

http://www.professionalequipment.com/ex ... ermometer/

having a good cross check tool like a quality IR temp gun, and a decent multi meter, sure helps find the truth as far as a defective gauge or sensor
image_493.jpg

viewtopic.php?f=50&t=3110&p=8296&hilit=multi+meter#p8296

http://garage.grumpysperformance.com/index.php?threads/cooling-off-that-c4-corvette.3954/#post-10553

viewtopic.php?f=44&t=808

viewtopic.php?f=44&t=700

viewtopic.php?f=80&t=728&p=9217&hilit=sensors+resistance+ohms#p9217

viewtopic.php?f=44&t=1082

viewtopic.php?f=57&t=940

viewtopic.php?f=4&t=1337&p=2921&hilit=infrared#p2921

http://www.aa1car.com/library/electric_cooling_fan.htm
 
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Thanks Paul that is why I am doing the tests first. I have all of the tools except a air fuel meter can you recomend one?
 
Hey grumpy with engine running at 220-230 is is safe to run? Can I run it for the tests? Also as for reading the spark plugs I have the E3 plugs in I dont think they read as the stock ones do. Is that correct?
 
heres a thread on the f/a meters

viewtopic.php?f=50&t=1853&p=4848#p4848

you can run the engine for tests, short duration, but if you suspect a blown head gasket, Id restrict driving the car until the problems isolated and repaired or the problem will get worse and further damage will occur
 
Ok so here are the results on my testing.

I did a pressure test on the rad and it held 15 PSI for 15 minutes. Did not budge......GOOD

I did a compression test on the cylinders and here are the results, This was done on a cold engine and the exhaust rocker was connected.

Cylinder Reading in PSI
1 160
2 150
3 160
4 150
5 155
6 130
7 170
8 130

As you can see 6 & 8 were low. This is leading me to think the head gasket might be bad. I put a small amount of oil in the cylinder 8 and ran the test again. This time the reading was 175. This could be a bad set of rings. Not what I wanted to see. I then did the test agin on number 6 without putting in any oil and it also went up to 175. I then put some oil in number 6 and it agin went to 175.

I took the tool out and turned it over a few times to push the oil out and they both stayed at 175.

SO could both sets of rings have an issue or could the oil from number 8 have pushed into number 6 with the bad gasket to cause the rise in readings without any extra oil. Or could this be a warped head? I am not sure the head is warped as the spark plugs did read with some burn and the pressure tester on the rad was good.

So any thoughs? My next step I belive is to take the head off and look at the gasket and and pistons and check the bottom of the valves.

Thanks
 
you could do the exhaust gases, reactive dye test in the coolant, mentioned in the coolant test thread, for further proof ,before tearing the head off, but since it jumped up 40-45 psi psi with the oil added the oil obviously temporarily sealed a leak, it might be a cracked head, a bad head gasket or burnt valve, maybe a worn ring, the next step is pull the head and visually inspect then have a shop inspect the head and test it for cracks if nothings obvious (which it should be!)
 
Grumpy in your experience would two cylinders have the same low compression and then go up the same amount with oil going into one piston? Or is that more like a gasket?
 
you won,t know without a inspection, but logic tends to point to a head gasket, for the simple fact that only the thin sealing web of the gasket material between them is shared
 
That is what my thought was. I will start the tear down tomorrow. I will document it and take pics for your forum to hlep anyone else. Thanks
 
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