[alanmay0]

OK this picture does not show the use of the two rubber spacers/O rings or what ever. see attached picture

[Murf]

Originally Posted by alanmay0

OK this picture does not show the use of the two rubber spacers/O rings or what ever. see attached picture

Is that a pic of your car? If not it doesn’t real pertain to anything here.

ETA you would be looking for metallic particles in the filter. Indicating some sort of engine issue.

Does it puke coolant when you pull over with the gauge pegged?

The more info you can give the better the advice will be.

Good luck!
Murg

[alanmay0]

No that is not my car that is a car on youtube that a guy is showing what can can cause the pontiac to overheat. I was just asking is those black rubber things are needed in the water pump. I have never used them, or knew they existed, until seeing that youtube video. The car does not puke water when I stop. I do take the temp reading with the laser gun and it is 245 plus degrees. I have not yet cut the oil filter open but was getting ready to but decided to get the temp reading of the center exhaust manifold when it hits 220 degrees as another on this site wanted to know. Well I started the engine and was letting it warm up. The temp at the thermostat housing was reading about 135 degrees so I was going to take the radiator cap off to see when the stat opened and if the water was flowing. well when I gently began lifting the radiator cap when the engine was only showing 135 degrees it nearly blew off with force in the radiator. So lots of anti freeze came bursting out but I was lucky enough to get the cap on before it all came out. Cant understand why the radiator would be filled with pressure or hot anti freeze when the thermostat had not yet opened. Any one have any ideals??
thanks again

[68WarDog]

What pulleys system are you running? Hopefully it's not one of those slow water 6" crank pulley, coupled that with a 8" water pump pulley.

[alanmay0]

it is a 8" water pully with a 7" crank pully

[Half-Inch Stud]

Originally Posted by alanmay0

it is a 8" water pully with a 7" crank pully

Not thee problem, but smaller water pump pulley could help.

[alanmay0]

will cut oil filter open tomorrow. no it does not puke water

[John V.]

You mentioned you are running 60:40 coolant to water mix?

That will raise the boiling point but generally, I believe water may provide a bit better heat transfer. And if you haven't tested the mix, maybe you are running an even higher concentration?

I suspect a mechanical issue but just suggesting something else to consider. I realize you are in Texas and perhaps 60:40 is common there because of high ambient temps. Worth checking perhaps.

Next, you mentioned the intake crossover was blocked which is a common practice especially since our old Pontiacs mostly aren't driven in winter cold.

But a '67 would have used a RH exhaust manifold Heat Riser Valve. Just curious if yours was eliminated. With a blocked crossover, a stuck closed HRV would be a big issue but I'm thinking a stuck partially closed HRV couldn't be good for engine performance generally and probably cause high temps.

Hopefully yours has been removed or permanently opened.

You confirmed that you have the 8 bolt style Flowkooler water pump and you used the early style two divider plate package. As others have stated, the rubber seals were not used with the 8 bolt and assume the Flowkooler wouldn't need them either.

I think lots of folks have used a Flowkooler pump so I assume no issues there. For stock engines and radiators I have always been a proponent of stock pumps as they were designed for a specific flow rate to give the coolant residence time through the radiator. Pumping through the radiator too fast would not allow time for the best heat transfer.

When my engine was rebuilt, we used lifters I had purchased in the early '90s. One of them never pumped up. On disassembly it was discovered the lifter had come apart. IIRC, I was told lifters from that era had issues. The fresh engine had only been run for some minutes but we decided to replace the cam along with the lifters rather than worry about a wiped lobe. But seems to me you would know if you had a lifter/cam issue at start up well before it got hot.

Some years ago, I remember a guy was overheating. His upper rad hose was too long and trapped air (think an upside down drain trap effect). IIRC, he shortened the hose so that it wasn't arched above the inlet. That seemed to cure his overheating as the air was no longer trapped. Since you aren't boiling coolant, I would be suspicious of a temp misread because of air in the system but based on what you've done, aside from the hose configuration, I doubt air is your problem and the coolant really is getting that hot.

Since you saw a 53 deg F difference in center exhaust port temp from RH to LH head, I'm with 25stevem about the head gasket on the LH side and also Joe's Garage who judged the no. 5 plug looking a bit too clean vs. 1, 3 , and 7.

Your engine builder should be able to test for a head gasket leak. Since he re-ringed the pistons, did he install new head gaskets?

[68WarDog]

What's the overbore with your 670 heads? Have you noticed any sounds of detonation ? Would you be able to run some 110 octane fuel?

[alanmay0]

The cylinders were bored 30 over on a previous engine rebuild. This rebuild cylinders only honed. No detonation at all. Don't know if I could run 110 fuel because in Texas you can't get it. Remember before the recent rebuild, 150 miles ago, I drove this car from Florida to Texas with no problems. although the temp sending was not working I detected no overheating problems at all. So something changed with the rebuild, I used the same water pump because it was a good one and worked fine. Very very confusing. I can not think of any thing else to try. So any help appreciated.

[John V.]

Is it possible the electric fans are wired to spin in reverse?

Not sure that would cause the extreme overheating but surely wouldn't help.

Check to be sure they are pulling air thru the radiator, not trying to push air out of the engine bay thru the radiator.

[alanmay0]

they are wired correctly they are pulling lots of hot air that is for sure. remember I removed them and put the 7 blade clutch fan on and still temp climbed to 250.

[alanmay0]

Thanks for all of your information. Yes new head gaskets were installed. Again today I rented the tester for telling if exhaust gases were in the radiator. I checked and double checked with this tester and could not get the blue solution to turn yellow. I did test the solution buy holding it by the exhaust pipe and it did turn yellow. Yes the heat riser is frozen in the open position. Today after adjusting the carb. the 53 degree difference between exhaust sides seems to have corrected itself and they both pretty much read the same. So today i also checked the compression and all cylinders were between 145 and 150. So you know I have an aluminum radiator and two 12" fans from Butler Performance who stated that this combination would cool any car on the road today. Not Mine. When the thermostat opens you can see the water flowing and the heater blows very very hot air. So the pump is working. Is it working too good maybe. I can tell you that the temp, when taken with the laser temp gauges, at the thermostat housing and again taken at the water pump intake where the lower radiator hose connects to the water pump are basically the same. The guy at Butler told me that a radiator can take about 30 degrees out of the water temp from top to bottom. This is not happening with my engine. The temps are about the same. Meaning that not much heat loss through the radiator. Both 12" fans are on but not pulling enough heat, or pulling all they can. Like i mentioned in my earlier post I have tried a different radiator and i have tried using the 7 blade clutch fan with no changes what so ever. So any suggestions you may have would be appreciated. I was thinking of tomorrow removing the plates under the intake manifold so that the exhaust could flow through the intake, dont know if that would make a difference. I am aware of what you are talking about with the large top radiator hose. I have seen those. Don't think mine is that long. I have been told that I might have a air pocket but I have changed the radiators and anti freeze so many times and flushed the system that I find it hard to believe that an air pocket is possible. I could be wrong. Any help appreciated. Thanks

[Gary D]

Hi, First thing I would check is combustion gases/heat getting into your coolant system. I fought a heating problem for a long time and it turned out o be a bad block that had been repaired with a sleeve and I believe that hid the real problem. I bought a rebuilt 455 and had to rebuild it again. A bad Craigslist experience!! Long story short after trying every cooling combo available I finally checked for combustion escaping into my coolant and solved the problem. Destroyed that block as not repairable, transferred all my parts, problem solved. Just a thought!

[78w72]

Originally Posted by alanmay0

Did the test for exhaust gasses in the radiator, could not turn blue stuff yellow.

Originally Posted by Gary D

Hi, First thing I would check is combustion gases/heat getting into your coolant system.

FYI: he has checked that