Motor is getting hot

Asked by Mar 01, 2017 at 06:10 PM

Question type: Maintenance & Repair

So my radiator is new my hoses are new I took off the
thermostat filled my care with all liquids 50 50 and it still
gets hot and turns off my belts are new the fan is solid has
oil no leaks it's a 1968 cuttless supreme what else could it

9 Answers


You need to run with a thermostat. Try a 180°. Also when the cooling system is filled it needs to be purged from air. You have the heater set on hot so it will circulate threw the heater core. Hear is a video....

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Yep, check the water pump as Tom says too.


Following all the other advice also use a good cooling system flush just in case some of the cooling ports in the engine is clogged. Prestone Super Flush is really good.

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I ran on of these rocket motors for years and they do run warm. The internal design is not the best for oil cooling, as it runs hot (warm as I say) the oil ports get clogged (oil bubbles then hardens) and cakes under the intake manifold on top the oil windage tray and then stops up the oiling passageways. I pulled my intake off cleaned out the caking and opened up the oil passageways. I added a huge after market radiator and bought the biggest trans oil cooler I could find which was 1/2 the size of the radiator, ran my transmission lines to it only, not to radiator too, as Rowefast said I used a 180 degree stat. Some may not do this but I also drained my oil and filled the motor with diesel fuel for a 24 hour soak and drained and repeated 2 more times (days) to rinse it out. Then did a oil/oil filter change and tried it out and it cooled normal after that but if it did not I was about to add a oil filter relocation kit and another oil cooler for engine oil. Make sure you have a good radiator fan shroud.

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P.S. I did put a good water pump on and not a cheap auto-zome rebuild unit, they are fairly cheap new. Also some of these had owner wanting more power out of them threw the years so make sure you do not have under drive pulleys on it, if you do go back to stock.

I have a good water pump I believe the problem is somewhere in the block buy what could it be


The oil passageways are tiny by Todays standards or at least at the same time was rebuilding a Honda Civic Head, which I noticed and compared the oil drain passageways in the Honda block were about 1/3 larger and when I went back to the cutlass motor I felt this was a big issue. What is going on is the oil is going to the top side and cannot drain fast enough and then collects under the intake and on the heads but then it has time to sizzle on the heat of the motor,the windage tray acts as a frying pan, stops up the drain passageways pretty fast. The black deep fried oil under my intake was hard as a rock I had to break it in chucks to get it out. I used rods to clean out and push threw the oil drains and I had to fill up the motor with (intake off and oil drained and oil plug in) diesel fuel poured in from the open intake, made sure I had enough to cover the oil passageways and let it sit 24+ hours then used tiny brushes for bottles, gun cleaning ect any small brushes and rods and metal wires of different gauge and strength to get threw the oil drains cause they have to bend and come back out too, then drained it and poured some in to clean a little more, then put oil plug back in and filled motor back up again came back the next day & did it again the next day, after the third time I think the fuel sitting in the oil drains finally did the trick, they opened up and drained fast so I poured in a few extra gallons to clean it some more let drain put oil plug back in came back a few hours later, drained again then started adding oil. I also changed the oil after about 100 miles.

1 people found this helpful.

If yours is real bad (and I should have too) pull the oil pan and check it out and oil pick up tube & screen, I had oil pressure but really I should have pulled the pan to clean it. My oil looked dirty just after 100 miles and after that I started changing it once a month, no mater the mileage, I did not drive it but about 1000 miles a month and it would get darker that fast, otherwise ran like a champ.


Is it also turning off, but cranks back up after it cools off? Might need a pick up igniter unit module in the distributor, mine had a points eliminator ignition conversion kit. If you have point they may need cleaned or new ones and the coil may need a new unit as these are age/heat sensitive.

1 people found this helpful.

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