Overheating question

[DOMINIC]

My first post so please forgive me. Without writing a history novel, I am not the owner of this 62 409 dual carb number matching everything vehicle. I am a shop owner/technician that is very familiar with engine builds and diagnostics. However, this is my first encounter with a 409. This car has been overheating for the past 20 years that my neighbor has owned it. This summer he let me touch it. Engine overheats within 10 minutes of idling. Initial diagnosis, HC's in the cooling system. Removed engine and began tear down. Found severally warpped heads and block along with alot of pitting. No question I was on the right track. Internals of engine were in excellent condition along with "newer looking" .060 pistons. Off to the machinist to inspect for cracks and sonic testing. Results were good. Milled block and heads. Reassembled engine and hooked up engine on an actual "engine running stand". Went through all the motions,waterflow,timing advance, etc,etc,etc, Engine now takes 20 minutes to reach 240 degrees. I no longer have HC's. It is just a nice even steady climb in temp until it boils over. After ruling "almost" everything out, A final compression ratio reveals just over 12 to 1. Is this my problem due to the .060 over bore ? And yes I am using 104octane . HELP HELP PLEASE HELP!

 

[DonSSDD]

The experts will answer after me, but what thermostat, coolant, and rad are you using? I assume you have a good temp gauge, did it actually boil over on the stand?

Don

 

[tripower]

I hope you did not deck the block and erase the suffix code? Does it have a fan shroud? If so is it the short one 4-3/4". Does it have a clutch fan and is the fan 1/2 in/out of the fan shroud? 160 * thermostat with correct 409 radiator? What is HC's?

 

[DOMINIC]

Nice and steady climb. Yes it will boil over. 180 ,160 and no stat at all. Water is flowing in proper direction. I slowed it down and sped it up. No change. Green coolant, Aluminium rad,electric fan,independent temp guage. Absolute no car in this equation. Dom

 

[DOMINIC]

Code is still stamped

 

[tripower]

Get rid of the electric fan put a clutch fan and correct fan shroud. Also need to run the correct pulleys.

 

[DOMINIC]

Please read the opening statement.

 

[tripower]

Please read the opening statement.

I did

 

[DOMINIC]

Engine is running outside in sub zero temperatures. I know a copper radiator and a fan shroud will not help the situation. Aluminum radiator is doing its job with proper heat transfer. Has original pulley's . Tried a smaller one on waterpump per one of our members. no change.

 

[Ronnie Russell]

If you are basing your conclusion on idle to 2,000 rpms on the run stand , you are not seeing the true temp range you would see with the engine in the car. There is nothing like moving a lot of air to get decent cooling. I'm sure you have had success with electric fans but it is hard to beat a good old fashioned fan clutch and radiator shroud. I would not be surprised if you don't have a cooling problem now that you have addressed major issues. I realize you want to find problems now, on the run stand, but putting the car back in the car and tuning from there would get you true temp readings. A pet quirk of mine is ----- engines idling for long periods of time. I hate that. No matter who owns it. Computer cars? A whole different story. You have addressed the issues that could cause a problem. I applaud you for running checks with different therm. and even no therm. During the summer I would expect to see no difference in coolant temp , therm or no therm. An efficient radiator and plenty of air flow should and I believe , will, allow you to run at 200 dg during normal driving conditions. Now, of course this is only one opinion and may be incorrect, but that's the way I see it.

 

[DOMINIC]

In theory you are correct and I agree with you. But based on all of my past expieriences, I never seen an engine overheat on a dyno or an engine run stand so quickly. Please keep in mind, that this is back to the original problem before it warpped everything. Fan blade ,clutch,shroud issus and clearances were all inspected before engine removal. Proper steps were all taken in the vehicle.Original radiator is a copper high efficient 4-row. Iay can't believe putting this back in the car is going to be the answer. I have to be missing something. I don't like cars sitting at idle either but,,it absolutely should not be running this hot outside my building on a 10 degree day not surrounded by heat or sheetmetal, and getting to let's say 220 in 15minutes. If I let it run it will boil over. I don't know. I'm stumpped.

 

[tripower]

In some cases there is quite sludge build up in the block of these old engines. Was it flushed? Also some of the members here have used the aftermarket panels that close up the core support to the grill and force the air through the radiator. I know they make them for 61' but not sure about 62'.

 

[1961BelAir427]

I can't help but wonder if the machine shop missed a crack in the block or heads. Have you done a lead down test since it was rebuilt?

 

[DOMINIC]

I had the block boiled while at the machine shop. Keep in mind it is still out of the car.I read here in some instances that guys have drilled out those coolant passages at the top of the block. I did not do that. Sorry I have to run my kids to practice!

 

[tripower]

On the early 348's the heads did not have water jackets around the spark plugs. Its not uncommon for someone to put a set of the later heads with cooling on these engines but they have to be plugged to do so. By chance could these heads have been plugged there? Just a thought.

 

[Ronnie Russell]

Dominic, you're stumped,,,, me too. The only thing I can come up with is cam installed incorrectly during the original re-build. You know yourself that 4 dg plus or minus at the crank can make a big difference , not just performance but cooling also. Can you play with timing by adding or subtracting advance and maybe get a clue?

 

[Jim409_Pontiac]

To follow up on Ronnies post, timeing is a huge problem with overheating on these engines. Even though you have said this is a complete numbers matching engine it is over 50 years old. You might want to check the damper to make sure the marks are correct. Some people use a small block damper that will work, but the marks have to be changed. Could have happened sometime in the history of this engine? Also the damper could have turned. Easy to check.

 

[skipxt4]

Is it possible, the water pump impeller, is defective? If it's corroded, coolant will not circulate correctly.

 

[tripower]

Is it possible, the water pump impeller, is defective? If it's corroded, coolant will not circulate correctly.

Or if it was a rebuilt with tin impeller instead of cast iron or Chinese repo.

 

[Ronnie Russell]

Dominic, my mistake. After re-reading, ,,, you had the block decks resurfaced, meaning - full rebuild-. so I'm sure you I.D. cam and degreed during re-assembly. There were a bunch of stock type timing gear sets sold some 10 to 15 years ago that were supplied with truck crank gears. Meaning retard from pass. car application. But, degreeing the cam always tells the whole story. You also say you checked water flow so, I got nothing else. Sorry.