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Keane165's 1970 LeMans

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Car running hot


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I have a 69 grand prix with a 428 that's been bored 30 over and its running hot it's running around 225 230 I've changed the water pump and the tubes behind the water pump the thermostat and I bought a bigger radiator and a new clutch fan and I took it back out and sent it to the builder and he said that he can't find anything wrong with it any suggestions please advise me 

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Hi Juan - welcome to FP and the madness.

Where in Michigan are you from?

What temperature thermostat are you running? I run a wide mouth 180 thermostat from Mr. Gasket in my 462 (.030 over 455). I have a factory 4-core radiator running a factory clutch-fan.

The water pump could still be an issue if the water impeller is not the correct distance / depth into the pump housing. It could be causing cavitation and not pumping enough water. While not a likely reason, it is not impossible.

It is also possible you could have an air bubble in your system and it needs to be "burped" to allow the coolant to flow properly.

Is your bigger radiator new or used? If it is used, do you know it has been hot tanked, repaired, or flushed? My concern is if it could be partially blocked as well.

Pontiacs like to throw out coolant when they get hot through the overflow tube, so I would recommend getting an inexpensive catch can that will catch overflow coolant and then suck it back when it cools down. I got mine for about $35 from Speedway Motors about 15 years ago. They are available through most performance and speed shop catalogs for cheap. It also keeps antifreeze off the ground.

How is your coolant level and mixture? Especially after one of your heat escapades and she's cooled down?

 

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Hello thanks for responding my mechanic has tried a 180 and  a 160 thermostat also the radiator is new so is the water pump fan blade and the clutch this is really a mistrey 

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Hey Juan, welcome. My 63' Grand Prix is running a 428 out of a 68' GP. This may sound really basic but have you tested the thermostat? My engine was getting hot so I put in a new 180 car quest thermostat. She was still getting hot. When I tested it I found that It was opening but really slow. A friend recommend a wide mouth Mr. Gasket 180 just like Frosty said. It actually did solve my problem. Good luck and keep us posted bud

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4 minutes ago, Wrongway said:

Hey Juan, welcome. My 63' Grand Prix is running a 428 out of a 68' GP. This may sound really basic but have you tested the thermostat? My engine was getting hot so I put in a new 180 car quest thermostat. She was still getting hot. When I tested it I found that It was opening but really slow. A friend recommend a wide mouth Mr. Gasket 180 just like Frosty said. It actually did solve my problem. Good luck and keep us posted bud

that was justA what i was thinking too Wrongway!!!:cheers:... ten bucks says you and frosty have found the issue!!:dancingpontiac:

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4 hours ago, Wrongway said:

Hey Juan, welcome. My 63' Grand Prix is running a 428 out of a 68' GP. This may sound really basic but have you tested the thermostat? My engine was getting hot so I put in a new 180 car quest thermostat. She was still getting hot. When I tested it I found that It was opening but really slow. A friend recommend a wide mouth Mr. Gasket 180 just like Frosty said. It actually did solve my problem. Good luck and keep us posted bud

Okay thanks for the information I'll try it

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Keeps us in the loop on what happens next!

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Ok I will do that once I get my engine back from the builder. But I'm not sure if that will work because I was talking to my mechanic and I was telling him what you guys had said about the wide mouth and he told me that he tried it without a thermostat and it still ran hot 

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Juan 

not a lot of things that can make it run hot 

you just need to check everything 

if your mechanic has ran the motor without a thermostat

then you need to be looking at the radiator , I am expecting he has the timing right and that the block was cleaned correctly and the water passages from the block to the head are open and clean

maybe when you get your motor back

justA stick a hose in it and make sure you have a nice unrestricted water flow

then all points back to the radiator 👍👍👍

and like frosty said keep us in the loop 👍👍👍 

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And how about a picture of your fan set up so we can see what is doing the cooling :cheers:

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Other than the .030 over bore...Is the engine still basically stock...?? 

Are you running a radical cam profile...??

Are you still  running the factory Iron cylinder heads...??

Is the Fan shroud in place/undamaged...??

This may sound crazy..Are you 100% sure the Temperature gauge is accurate...??

Something else that may sound crazy...When running an engine without the thermostat to help regulate the flow rate of the water...The water flow speeds up through the engine and it doesn't absorb the heat nearly as efficiently as it should... When it has some kind of a restriction (thermostat) to slow the water flow rate to allow for more efficient heat absorption....Something you might try...Instead of running a thermostat...You can try a water restrictor...Basically what they are is a round disc that looks like a washer that fits in the housing where the thermostat normally goes...But they they have different sized holes from larger to smaller and you can actually speed up or slow down the flow rate of the water thru the engine....Independently of the water pump flow .... Depending on what size you install...They are available as an inexpensive kit with different sizes included...You can get them thru someplace like Summit...

Might be something to consider....

Edited by TWO LANE BLACK TOP
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7 hours ago, 64 kiwi boni said:

Juan 

not a lot of things that can make it run hot 

you just need to check everything 

if your mechanic has ran the motor without a thermostat

then you need to be looking at the radiator , I am expecting he has the timing right and that the block was cleaned correctly and the water passages from the block to the head are open and clean

maybe when you get your motor back

justA stick a hose in it and make sure you have a nice unrestricted water flow

then all points back to the radiator 👍👍👍

and like frosty said keep us in the loop 👍👍👍 

Okay will do 

Okay will do 

6 hours ago, 64 kiwi boni said:

And how about a picture of your fan set up so we can see what is doing the cooling :cheers:

Okay 

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5 hours ago, TWO LANE BLACK TOP said:

Other than the .030 over bore...Is the engine still basically stock...?? 

Are you running a radical cam profile...??

Are you still  running the factory Iron cylinder heads...??

Is the Fan shroud in place/undamaged...??

This may sound crazy..Are you 100% sure the Temperature gauge is accurate...??

Something else that may sound crazy...When running an engine without the thermostat to help regulate the flow rate of the water...The water flow speeds up through the engine and it doesn't absorb the heat nearly as efficiently as it should... When it has some kind of a restriction (thermostat) to slow the water flow rate to allow for more efficient heat absorption....Something you might try...Instead of running a thermostat...You can try a water restrictor...Basically what they are is a round disc that looks like a washer that fits in the housing where the thermostat normally goes...But they they have different sized holes from larger to smaller and you can actually speed up or slow down the flow rate of the water thru the engine....Independently of the water pump flow .... Depending on what size you install...They are available as an inexpensive kit with different sizes included...You can get them thru someplace like Summit...

Might be something to consider....

When I bought the car last year the engine was locked so I had my mechanic pull it out and sent it to a engine builder and it came with aluminum heads so I just kept them on but  besides that everything else is regular  and thanks for the info I'll try anything I want to drive my car 

I'll try anything I want to drive my car 

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Basically very thing that’s been mentioned will and does effect coolant temps. One additional thing that can cause temperatures issues is the bottom inlet hose! Sometimes the bottom hose for several reasons can collapse! This restricts flow, causing overheating. 
In the end you need to do three things. 1.Verify that the temperature is what the gage says. 2.Verify that the flow of the coolant is proper and 3.If the temp is right, but the flow is not, than you must verify there is no blockage, the pump is functioning properly, the air flow through the radiator is correct, that the fan is correct in both type as well placement. 
How big is the radiator? Last, but not least. Have you looked at the coolant? Is it clean or dirty/oily head gasket leaks can cause severe temperature increases while not impacting actual performance in the short term.

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56 minutes ago, Last Indian said:

Basically very thing that’s been mentioned will and does effect coolant temps. One additional thing that can cause temperatures issues is the bottom inlet hose! Sometimes the bottom hose for several reasons can collapse! This restricts flow, causing overheating. 
In the end you need to do three things. 1.Verify that the temperature is what the gage says. 2.Verify that the flow of the coolant is proper and 3.If the temp is right, but the flow is not, than you must verify there is no blockage, the pump is functioning properly, the air flow through the radiator is correct, that the fan is correct in both type as well placement. 
How big is the radiator? Last, but not least. Have you looked at the coolant? Is it clean or dirty/oily head gasket leaks can cause severe temperature increases while not impacting actual performance in the 

Yes I've checked the fan and water pump checked the head gasket so we pulled the engine back out and I'm waiting for the builder to get back with me 

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3 hours ago, Fitzy said:

I've been resisting the urge to chime in, but it sounds like you're reaching the Twilight Zone at this stage of trying to work out what's going on. As I posted some time ago whilst in the throes of my 389 rebuild, I took it upon myself to drill out the factory blocked coolant passages at the front of my block. These are the ones that go from the block and up thru the heads. While I was there, I drilled and cleaned out all the other coolant passages, as years of crud had built up all manner of crusty deposits. In fact, my old water pump was so gunked up with crud that it would not have pumped anything. The previous owner had, it appears, in desperation removed the thermostat in an attempt to help cool the beast. I've only just refitted the engine and haven't gone for a decent drive yet, but all indications so far point to a well cooled engine. For the record, I fitted a FlowKooler water pump and a custom made radiator with larger cooling tubes and more fins per inch. Strangely, my car has never had aircon but has a factory 7 blade fan, whereas non a/c cars apparently came with a 5 blade. Perhaps the previous owner tried that trick too. Anyway, ensure your ignition timing is correct and that it's advancing as it should as revs rise. Plenty of airflow to radiator? Sounds to me like a blocked radiator if everything else checks out okay. Testing the thermostat by heating it on the stove in a saucepan in water and observing it's action is also recommended. 

Even though my block was hot tanked, the decades of calcified deposits in the water jacket were never going to shift. I read somewhere that the stuff they put in swimming pools can be sent through your cooling system and will loosen all that crap up, but I'd be treading carefully in case you dislodged so much stuff that you blocked something else!

Thank you for the information I think that you're on top something because the builder is telling me that he can't find anything wrong with the engine but I'm like it has to be I've bought two different radiators a3 row and it still ran hot so I went and ordered a 4 row and it did the same thing but I'm going to forward this to my mechanic thanks again 

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Here is another useful reference from Butler Performance regarding water pumps. Again, something else you can share with your builder.

https://butlerperformance.com/n-13390-pontiac-water-pumps.html

image.png.660c265bc3db8b0ed267178ccd324f79.png

 

Finally, here is the Butler checklist of things to look at for overheating conditions

Overheating? - Try our check list

Cooling has long been an issue in performance enhanced gasoline combustion engines. We recommend engine temperatures not in excess of 180 degrees (F). The cooling system in your Pontiac engine is very simple consisting of only a pump, thermostat, fan, and radiator. Failure of only one of the components in the cooling system will result in excessive engine temperatures. Excessive engine temperature can damage an engine in mere seconds. Since different metals expand at different rates with increased temperature you can be sure that engine component clearances are altered, causing wear or premature failure. The most harmful effect of high engine temperature is detonation. Detonation for even a short period of time could damage your rod bearings or possibly even puncture the top of a piston. When attempting to resolve an issue with the cooling system one might start with a checklist covering these subjects:

Is there a sufficient amount of coolant in the cooling system?

Is the thermostat stuck?

Is the radiator clogged? (Inside and out)

Is the radiator sufficient for the application?

Is there a fan shroud on the radiator?

Is the fan close enough to the fan shroud?

If the engine is freshly built were the proper gaskets used? (head & intake)

If the engine is 1969 or later are the plate and sleeves installed in the timing cover?

If the engine is 1969 or later are there good o-rings in the sleeves inserted in the timing cover?

If the engine is pre 1969 are both plates installed behind the water pump?

Is the impeller of the pump as close as possible to the plate behind it?

Is the air/fuel mixture of the engine too lean?

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Yes the flow was checked I had the block flushed and two  brand new radiators but I'm going to pass this info to my mechanic thank you 

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  • 1 month later...

Thanks for the information and yes please send pictures 

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Thanks for the information please send pictures 

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