Overheating but only when keeping engine above 2k rpm

dgw8022 said:

....... when the hose did blow I got most of the water in a bucket when I poured the bucket out at the bottom was this rust like paste rather nasty.

I'll do the flush first then if I still have a problem I'll have to think of something else.

Thanks for the replies everyone I'll keep you posted on what I find.

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You might wanna check the differences between doing it yourself w/ auto store type flushes and a pro job. If it's that thick like paste that block sounds really clogged to the max. A shop probably has something better to eat that rust away and power flush it out compared to a garden hose and conventional flush which I doubt will be up for that job.

bnickel said:

what is you water/coolant mixture? if you run more than 50% antifreeze the engine won't cool right, coolant is actually a misnomer it's just antifreeze but actually lowers the boiling point as well the freezing point. i generally try to run about 60-70% water and the rest antifreeze. a few weeks ago i got the mixture wrong after pulling the radiator to fix my fan cracked fan shroud, i put too much antifreeze back in and it ran hot all day, i drained some out and filled it back up with plain water and haven't had a problem since.

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I will agree that too much coolant will lower the boiling point but it says right on the container what the boiling point will be at a given mix and pressure.

Did you not mean to say that straight water will cool better? This statement has nothing to do with the boiling point. How well a liquid transfers heat and what its boiling point happens to be are 2 distinct characteristics that don't affect eash other.

anti freeze also effects the surface tension of water as well as the boiling point, the main reason to use anti freeze is to prevent freezing as well as to lubricate the pump bearings and to prevent corrosion, using anti freeze to help the engine run cooler is not what anti freeze is for. using too much anti freeze will cause the engine to run hot or at least hotter.

and yes rasing the boiling point will effect how well the mixture cools the engine. running a higher pressure in the system also raises the boiling point as well.

does the car run ok at speed, or does it feel like it's down on power (before it starts to overheat). retarded ignition can cause some overheating, but the power loss would also be evident. Is the vacuum hose attached to the distributor?

One point I missed, do you have the right radiator cap on that your engine calls for? (just to cover all bases)

Also, after you refill your radiator after a flush let it run till you see the thermostat open (your coolant will suddenly drop), add more at this point till full and have your heater running on high to get all the air out of the lines. (I assume you allready know this but threw it in anyway)

Go with the pro flush, can't cost that much, explain to them that the motor sat a long time and is probably more clogged than most they do. Won't hurt to tip the guy that's gonna do the job a fin or so. I'd even tell them to give it a double flush.

I got the feeling that block has chambers totally closed off to any coolant flow and I would think that difference in heat buildup in any one area could possibly crack your block.

If what they use is to caustic for the hoses to leave in long, you may want to after the first flush is finished, unhook your heater hoses and run a by pass hose on the water pump and have them now do a longer flush thru the block to really eat this rust out of there. Having to replace your upper and lower hoses if this solution is highly caustic would be no big deal if it cures your problem permanently.

I spent a number of years as a ship yard welder and believe me I've seen that rust has no limits on how much it can build up. Try a 180 degree thermostat after the flush, check also to see if you have the right pressure radiator cap and let us know how you eventually make out.