[alanmay0]

This may be a long description of my problem so just bare with me. I have a 1967 GTO. The engine has just been rebuild and it runs great. My problem is that it runs really hot. So hot that I can only drive it, at the most, 10 miles before it pegs the temp. gauge at 250+. It is not the gauge I have a infra red temp gauge that I check the temp with. I check at the thermostat housing to get the engine water temp from and then agian I check at the water pump inlet where the bottom radiator hose connects to the water pump. I do get about a 20 degree drop between the two locations showing that the radiator is taking out heat. I have a Butler performance aluminum radiator with two 10 or 12 inch fans, cant remember exactly which ones. This is what the guy at Butler suggested for this car. I have each fan set up on its own relay so if one stops the other will still run. I have a 160 thermostat in the car now. I did have a 190 and there is no difference in engine temp.. I have new water hoses and I have the spring in the bottom hose. I have tested the in dash temp gauge and it is working correctly. Remember I check the engine temp with the infra red temp checker so you can actually take the gauge out of the picture. The fans are set to come on at 160 and they do. The thermostat does open at 160 also. The engine has new anti freeze set at about 60/40. The water pump is a flow kooler, which is suppose to be one of the best. I have corrected the divider plate so that there is very little space between the flow kooler and the divider plate as seen on many youtube videos. I have done a little filing on the divider plate so that the hole going to the heads lines up. Like I said the engine hits 250 degrees in about 10 miles at most on a 85 degree day. At this point I have to pull off of the highway and let the fans run for about 20 minutes to pull the heat out of the radiator water before I can go another 10 miles. Now I only did this yesterday because I went to a car show. In the morning it was cooler so I only had to stop twice during the 50 mile trip but coming home when it was 85 I had to stop several times. Will not drive it again until I can figure out the problem. This is where I am hoping someone on this site can help me. In an effort to fix the problem I removed the radiator and fans from butler and replaced with another aluminum radiator I have and installed the 7 blade GTO cooling fan with shroud but it still overheated. I can say one thing, I belive that the 7 blade fan pulls much more air through the radiator than the two electric fans. Just my belief.

When I had the water pump removed for the 5th time I removed the thermostat and housing and ran garden hose water through the opening where the water would flow from the water pump into the heads. This is on the left side of the water pump housing looking at it from the front of the car. I could see that the water flowed through the intake manifold, where the thermostat is housed, and it came out through two holes on the right side of the water pump housing. This indicated to me that there is water flow through the heads. I Also turned on the heater and the heater blower motor inside the car and it was blowing air at around 170 degrees when the engine was hot. This indicated to me that the water pump was working. Also when the thermostat opens I can see water moving in the radiator. It does not seem to flow as fast as my other GTO flowed but no was to determine flow speed, that I know if.

Now one thing that I just noticed while watching another youtube on water pumps for 67 GTO's, for the first time is that this guy opened up the water pump on his pontiac 326 engine and inside the water pump housing there were to rubber seals, I guess, one at each hole inside the water pump housing. Looked like one where the water is directed to go through the heads and the other where the water comes out of the heads back into the water pump.

I have never seen those rubber seals used before on a GTO. I owned another 67 GTO and replaced and worked on the water pump and never used the rubber seals. also when I had the engine rebuilt the rebuilder did not install the rubber seals but he did give them to me with the other parts that were in the gasket kit that were not used.

So Should I use the seals or not. Has anyone else ran into similar problems with over heating and can anyone have any other suggestions for me to try.

I think I have covered everything in this post to explain my situation. Ok for now the timing is set at the factor 6 degrees BTDC and I am running premium gasoline. I have the quadrajet carb. and I think the air fuel ratio is correct.

I was told by a guy at butler performance that I needed to set total timing at about 32 because of the fact that in Texas I can not get gas without ethanol in it. As far as I know the compression of my engine is still 10.5.

OK that's it any help or suggestion will be appreciated.

alan

[max 93]

Did it always run hot or did it just start? Might want to give more details on the engine rebuild

[alanmay0]

I bought the car and then started a total restoration not having driven it much. At the time I bought it the dash temp gauge did not work so dont know if it got how the few miles i drove it. The engine rebuild was just a normal rebuild. It appeared that the engine had recently been rebuilt. It was very clean when torn down. did not need to be bored out. So what could have been done in a normal rebuild, new bearings, rings, valve job new oil pump, fuel pump. I added aftermarket ac but have not used it because of the overheating condition. If you want to know more about the rebuild just ask questions. So what can happen during a rebuild that can cause the engine to run very hot after a few miles??? Thanks

[PunchT37]

Originally Posted by alanmay0

I bought the car and then started a total restoration not having driven it much. At the time I bought it the dash temp gauge did not work so dont know if it got how the few miles i drove it. The engine rebuild was just a normal rebuild. It appeared that the engine had recently been rebuilt. It was very clean when torn down. did not need to be bored out. So what could have been done in a normal rebuild, new bearings, rings, valve job new oil pump, fuel pump. I added aftermarket ac but have not used it because of the overheating condition. If you want to know more about the rebuild just ask questions. So what can happen during a rebuild that can cause the engine to run very hot after a few miles??? Thanks

I have seen a lot of engines run hot after a rebuild. But, yours does seem excessive. Tight piston to wall clearance and rings can add a lot of heat until broke in.

[alanmay0]

I think it just started after the rebuild. did drive it from florida to texas but the temp gauge was broke so not sure what temp it was running at. thanks. I have given all the info i can think of if you need more just ask me. thanks

[Half-Inch Stud]

Originally Posted by alanmay0

I think it just started after the rebuild. did drive it from florida to texas but the temp gauge was broke so not sure what temp it was running at.......thanks

Surely you opened the Secondaries at some point, if it didn't ping hard from FL-to-TX then all is indeed well.

[alanmay0]

That was before the engine rebuild a few weeks ago

[John V.]

And ditto advancing the ignition timing. 6 deg BTDC may have been the factory spec. It was in '64, my mostly stock rebuilt 389 that runs very cool. But the engine also required leaded premium when new. Gas that is unobtainium today, the lead helped with anti-knock allowing more compression and retarded timing that meant more power output.

So increase the timing but not so much that you induce detonation. Advanced timing without induced detonation will help lower the temp.

I haven't checked my own ignition timing (it is on my to-do list) but I am fairly certain it is advanced beyond the factory 6 deg spec.

[25stevem]

Once any vehicle is moving more then a steady 30 mph on the road having fans running to move air thru a radiator should not be needed.
Above speeds of 30 mph leaves these possibilities and possibly in concert with one another.

1) restricted air flow.
2) restricted water flow.
3) coolant moving thru the radiator too fast.
3) improper air to fuel ratio at certain throttle openings/ load conditions.
4) low cylinder pressure / retarded Cam timing)
5) retarded ignition timing, part throttle / cruse timing of less then 35 degrees with vacuum advance hooked up.
6) restricted exh.
7) excess internal engine friction.

If your not running vacuum advance, therein lie’s a good part of your issue!

Since you have a thermal gun I would take the car on another drive on a road where you can pull right off once the coolant temp gets to 220 and I would jump out pop the hood and with the gun see what temp the center exh ports are reading and report back here with that info.

I would first however remove the filter and cut it open to look for signs of trouble .

I have also seen two electric fans mounted right to the motor side face of a radiator create a nice airflow restriction above 40 mph.
There must be a minimum of 2.5” between the motor side rad face and the face of the electric fan(s).

[PunchT37]

I believe those collars/seals are supposed to be there. Been too long since I saw an 8 bolt pump but the 11 bolt definitely has em.

[alanmay0]

Mine is an 8 bolt

[TedRamAirII]

Leave the cap off, run the engine and fill it with water, until about 1" below the cap. with the top at 135f I suppose there was NO WATER in the intake. The intake cant get hot, without hot water inside of it. As it warms up, the water should start flowing, when the thermostat opens.

[alanmay0]

Restricted air flow. I removed the electric fans and the radiator they were attached too and replaced with the aluminum radiator that came on the car and installed the 7 blade clutch fan and drove it and it still overheated
restricted water flow. I know that there is water flow because i put the garden water hose into the hole where the water pump would force the water into the head and the water flowed across the intake manifold and also flowed out the hold in the water pump housing after leaving the driver side head. I do not know how fast this flow should be but it seemed to flow out ok.
Like I said there is at least a 20 degree temp drop from the temp at the thermostat housing and the temp at the water pump inlet from the bottom radiator hose. The guy at butler performance stated that 20 to 30 degree drop is the most that a radiator could reduce the temp.
the timing is set at factory 6 degree BTDC with the vacuum advance disconected and plugged.
has a new exhaust 2.5". I did forget to say that when it was rebuilt the man did plug the exhaust crossover in the intake manifold so the exhaust does not flow through the intake manifold.
cant speak about excess internal engine friction and do not know how to check it. I do know that getting ready to set the distributor in the block the spark plugs were out and the engine seemed to turn over easy enough.
I am running vacuum advance and it is working.
what filter do you want me to remove and cut open. the oil filter?
I do not believe there is a 2.5" space between the radiator and the fans. This set up was sold to me by butler performance for this car it came with the fans connect to a fan shroud. again I switch to the 7 blade fan with shoud and it still overheated.
I drive the car and check temp of middle exhaust and report that back to you.
so do you know about using the rubber bushing in the water pump between the divider plate and the inlet and exit of the head holes.

[25stevem]

I would also like to know if the car is boiling over or if you have bubbles in the rad which would indicate cylinder pressure getting into the cooling system.

[alanmay0]

Good question I forgot to mention that I did rent the tester from the auto parts store and check for exhaust fumes in the radiator. the blue liquid did not turn yellow meaning that there was not exhaust in the anti freeze. No the car never boiled over.

[PunchT37]

6 degrees is too low for anything not stock. Bring it up to 12 and see what happens.

[alanmay0]

I will write this suggestion down and try it also. thanks. I have really tried everything I can think of. I am at my witts end. Out of ideals or things to try. The temp gauge just steadly climbs till it pegs out.

[TB1]

Originally Posted by PunchT37

6 degrees is too low for anything not stock. Bring it up to 12 and see what happens.

This, and as mentioned in Post #3 with out the vacuum advance connected and working the cruise timing would be very low with 6° initial and whatever mechanical advance the distributer is producing at the engine speed while driving down the highway. As an example full advance of say 20° may not be fully in until over 3000 rpm. so cruising around at say 2500 rpm you may only be seeing 6+15=21° total as an example

[alanmay0]

Even with the radiator cap off and the engine running it still climbs up to 250 just idling. does not take more that 10 minutes once thermostat opens.

[alanmay0]

no it does not boil over and I have not notices bubble in the system when running it with the cap off. thanks