The Stovebolt Site Forums The Shop Area The HiPo Shop Radiator Vendor question

Is it using coolant?

Where is this coolant going from the cracked heat or block?

Is the radiator getting filled with pressure?

I'm sure by now you have pulled the block drain plugs and flushed it real good haven't you? poked the holes with wire and dug around in them?

Does this truck overheat on the highway at a steady speed, or is it just idling around when it overheats?

Slow speed overheating is from lack of air flow, highway speeds is lack of coolant flow, in general, but not always.

The carburetor is not super lean is it?

You have the timing set close?, retarded can cause a lot heat.

Is the block bored out more then .060"? thin cylinder walls can cause extra heat.

I read that engines run on the dyno need the heater hoses hooked up and not capped off because the engines run hotter with them capped. Are yours open or looped together?

Hook a pressure gauge up to the radiator overflow tube and see if it climbs up over the cap pressure quick, thats a good sign of broken gasket or iron.

Joe

Thanks Joe,
I'll print this out and do it all before I panic and go buying another anything.
I do know the timing is just set by ear after tearing the heads off and looking for gunk in the water jackets. We didn't find anything significant, just a little bit of gritty debris. I was hoping to find and remove some rat nest material that I missed when cleaning out the 1946 radiator but no such luck.
My coolant system is complete including the heater and an overflow tank.
The status of the bore is unknown, I bought the engine used out of a 72 Blazer but its block number indicates it is a 80-85 car motor. The heads were bought off craigslist from a similar motor that had a recent rebuild and a rod knocking. Makes me wonder if the rod was knocking because the heads were not doing their job.
If there is exhaust gasses getting into the coolant, wouldn't the coolant also be getting into the exhaust? I suppose my compression tester could be adapted with a rubber hose to check the overflow tube pressure.

Until a compression leak blows wide open, it's a lot easier for compression/combustion pressure to get into the coolant than the other way around. A gasket or a crack that will leak 120 pounds of compression pressure, or a bubble of hot gas when the cylinder fires won't necessarily let any 15-lb. pressurized coolant go the other way. By the time coolant starts showing up in the cylinders or the tailpipe, things have gotten way out of hand. I've done the cylinder leakdown test, where a combustion chamber is pressurized with the crankshaft locked, looked for bubbles in the radiator, and found some pretty sneaky head gasket leaks that way, but you have to check all the cylinders individually.
Jerry

Most blown head gaskets I have seen or cracked heads, run quit a while before ever getting hot, once they blew all the coolant out, they got hot. But as long as we kept them full they ran fine.

How about a reverse rotation water pump, if the engine is a
'80-'85, wouldn't that have a serpentine belt with a reverse rotation pump? This is where I would go next after checking out the block drain plugs.


Joe

The original water pump came from the 1973 307 engine. The new one was bought for a 1980 engine. I just checked napaonline.com and the water pumps for both engines are the same number for a new true flow (part # TFW 44027) There is also another part number listed for 1980 (part # TFW 42089) at the same price so I am not sure which one they sold me. I will check the receipt when I get home. I did take the old one apart and inspected it for contamination, none found, and my observation of the pump design is that it wouldn't matter which way it turns. The fins would propel the water in either direction.

A couple of things to think about when doing calculations is the need to factor in
the atmospheric pressure of higher elevations.

This chart, for instance, at 5000 ft elevation, shows water boiling at 202.9 degrees and atmospheric pressure is 12.2 PSI.
Someone on another board implied that atmospheric pressure had no bearing on the boiling point because it was a closed system but wouldn't the air inside the system be from that elevation not from sea level?

http://www.webbpump.com/technical-s...eter-readings-at-different-altitudes.php

A good radiator shop in your area should also be able to tell you if the cap formula of 1lb adds 3 degrees to the boiling point holds true at your altitude. I think the altitude would affect this.

Any up dates on the overheating?

It has been too cold to do anything. I picked up another set of recently rebuilt heads and plan on putting them on this weekend. Fortunately I have a fleet of other cars and trucks to drive so I don't have to rush into anything.

Well, thanks to 1937chevypu's help the T'Mater is back on the road. We put the new heads on over the weekend and it is running at about 140 without the thermostat we forgot to put back in. Took it into town for pizza and she warmed up to almost 180 in the Dominos parking lot but went right back down when I took off.

Congradulations! Glad you are back up and running.

Over the weekend I installed my 4 core aluminum radiator that I got from the same guys you bought yours at and I am cooling fine. Granted it was only in the 40's and 50's but it never got over 185. I had to modify my bracket to fit the chevy radiatior and I also had to move it out towards the grill more. I can now have my electric fan on the motor side of the radiator. I have added pictures to my webshots account if your are interested.
radiator slideshow

That looks good. Aren't you going to have filling issues with the cap under the radiator support top? Are you installing an overflow tank somewhere else?

I am planning on intalling an overflow tank and there are only seven or so bolts that hold the front piece of metal on. I figure I can remove the bolts if I need to add water. The cap will come off very easily and I didn't have any trouble filling the tank staight from the anitfreeze jug. I haven't decided what kind of overflow tank to install. Any ideas?

I bought one at the local FLAPS and mounted it on the firewall. It was a little bit short in the supplied hose.

The saga continues!

I think I may have found my mysterious overheating cause.

My clicker torque wrench is a piece of crap. I was putting a new gasket set in my Barracuda this past weekend and got down to torquing the head bolts in steps 25lb, 50lb, and final 75lb, and didn't feel that much difference in the effort required to obtain each step. So I go to the old tool box where I keep all the old tools I don't use anymore and pull out grandpas old torque wrench and start testing. It seems that the bolts that were just torqued to 75 lbs with the clicker were only torqued to about 55-60 lbs.

Going back to the truck motor, where the bolts were torqued to 65 lbs with the clicker, would that explain why I run cool for a couple days and then all hell breaks loose with the heat? I put the old wrench on one of the bolts I could get to without tearing the engine down again and read approximately 40 lbs.

Should I replace the head gaskets for the third time? Can I get away with torquing the bolts to the proper torque without replacing the gaskets? Do you think this is a reasonable cause for my problems?

If you have suspected head gasket problems the safe bet is to replace it, if it's already leaking then correcting the torque may help but likely won't fix it completely.