"Thar She Blows!"--- Again

[Joe C.]

OK, here's an update to my thread "Idle To Overheat" of two weeks ago (not yet archived).Here's the old info again, before the latest episode:

1965 327/365, new DeWitts,new belts,new correct H2O pump,correct fan blade assembly,replacement fan clutch,new hoses,50/50 coolant mix,correct AC 13# cap, new reservoir tank,block .020" over,newly rebuilt (by me) distributor with correct can/weights/springs/advance cam,static timing 8* BTDC,new heat riser,idle speed 750RPM, all coolant passages thoroughly rodded and flushed (by me) prior to rebuild early this year. I calibrated temp sender to gauge to achieve perfect correlation @ 180* F. Ambient temp 88*.XXXXXXXXXXXXXXXXXXXXXXXXX I ran the engine from cold start, car stationary, with hood open (and the following day, closed). After 30 minutes run time, the temp climbed slowly and steadily to 1/16" past the third (213*) mark on the temp gauge. This was verified as 230* with an IR thermometer aimed at the thermostat housing. At this point I shut it off. It heat soaked to a verified 240*, but did not boil over.

LATEST EPISODE: Same as above, same ambient temp.,idle speed temporarily bumped to 900RPM,hood closed, except I substituted a beautifully, and newly rebuilt original FAN CLUTCH for my replacement unit. This time she ran for 35 minutes, with a gauge reading midway between the third (213*) and fourth (240*) marks on the gauge (measured @ 248* with the IR). I was just ready to shut it off when: "Ah, bejeesus, thar be the white whale!!" Not a major catastrophe, except that the resulting superheated coolant blushed some areas of my new underhood black paint. Anyway, I believe I have now run out of options. Maybe some more experienced folks can pull a rabbit out of a hat here. Are you sure that this is not normal--I can remember many old cars acted this way and overheated in traffic.

Sorry for the wordy post, but I had a lot of data to transmit so youse would get the whole picture.

Joe

[Bill Clupper]

Re: "Thar She Blows!"--- Again

One question, as part of your engine rebuild, did you verify the TDC mark on the crank damper to be accurate?

[Joe C.]

Re: "Thar She Blows!"--- Again

Yes

[Joe L.]

Re: "Thar She Blows!"--- Again

Joe------

Based upon your description of everything that you've already done and assuming that your timing is not significantly retarded, I'd have to guess that you have a cracked block, cracked cylinder head(s), or blown head gasket.

[Robert C.]

Re: "Thar She Blows!"--- Again

Joe, I have a 65 365hp air-coupe and after my new DeWitts and a 160d. thermostat the car will hardly reach 180d's w/ the air on. I asked my mechanic about your problem and the only thing that he said was that the guy who overhauled the motor might have set it up "to tight". whatever that means? Have you tried Mobil-1 oil. It will run cooler with it and not scorch at high temps.

[Joe C.]

Re: "Thar She Blows!"--- Again

Joe:

Engine runs fine, maybe even too smooth considering the lumpy 30-30. There is no water in the oil, no oil in the water, the plugs are dry and tan, no water vapor out the pipes. I like Bill's theory on possibly being tight. This motor essentially has no miles on it-- it has probably 4 hours run time on it. I changed the "run in" oil after about 2 hours run time, and filled with Castrol 10W-40. When I built the engine, I checked all bearing clearances with plastigage--all were within tolerances. I'll just put in the steering column and seats, drive it for a while, and let it "loosen up"

Joe

[Clem Z.]

Re: "Thar She Blows!"--- Again

do you have a fan shroud installed? obtain a rad pressure tester that installs on a cold rad and you pump up to pressure with a bulb and let it set for 4/5 hours to see if it looses pressure because it should hold. there is a chemical that you can put into the water that turns color if there is combustion gas in the water.

[Duke W.]

Re: "Thar She Blows!"--- Again

The "she's tight" theory is an old wives'tale, unless the engine was improperly assembled to something other than OEM spec. If everything is OEM or equivalent and set to spec it should not overheat at idle, but I'm scratching my head as to what it is.

Your initial timing is a little light. The spec for a '65 L-76 is 12 nominal with a range of 10-14. Take an IR reading on the exhaust manifold then bump the initial to 12 and see if the manifold cools a bit.

If the initial is 12 with 16@8" from the vacuum can (check the idle manifold vacuum), total idle timing should be 28. Did you check this with the light? With that setup and 900 RPM (750 is way to low for a 30-30 cam) the manifolds should only read around 500 and you should just be able to touch them for an instant.

Duke

Duke

[James G.]

Re: "Thar She Blows!"--- Again

I have seen new water pumps not pump correctly.
I have seen intake manifold gaskets incorrectly installed and block off water passages.
I have seen incorrect vacumn advance cans on distributors that throw idle timing all out of wack and create a major idle timing and heatproblems.
I have seen thermostats installed upside down there by not working.

Get a good night sleep, get out the service manual and review step by step what you just told us. Take the thermostat out and try another or none for the moment. Put a big fan in front of the radiator. You may have a 195 degree thermostat in there even though it says less. Once 240 is reached in a mid year, it is impossible to get it cooled down.

And finally,drive it as you said. it may be tight and needs driving breakin miles.
Good luck

[jim34671]

Re: "Thar She Blows!"--- Again

Is the exhaust system clear of any debris or obstruction?
Do you get a balanced resonanced feel from both tail pipes??
You never no what may creep in there from 'engine out to engine in' time.
Good luck

[Joe C.]

Thanks To All

You have given me much to consider. I will drive it, and check the temp. If it still runs hot, then I know I REALLY have a problem. Meantime, I will check a few things, and keep you posted as to what shakes loose.

Joe

[John H.]

Re: Thanks To All

What does it do on the highway? If the problem is isolated to idle cooling, the first thing I'd check is vacuum advance function; you need a can that's fully-deployed at idle, with full manifold vacuum on it, and a 900-950 rpm idle that generates enough manifold vacuum to fully deploy the advance can. If there's any question about the operation of your existing can, replace it with an Echlin #VC-1810, which will fully deploy at 8" Hg.

My (stock) '69 Z/28 has the same 30-30 cam as your L-76 and essentially the same intake, and I'm lucky if I can get 9"-10" Hg at a 900-950 rpm idle.

[Chas Kingston]

Re: Thanks To All

Double-check that you still have the rubber collar on the vacuum advance pin.

Geezer

[Bob Simard]

Re: Thanks To All

Not to be insulting, but you would not be the first to very carefully install the fan backwards.

[Clem Z.]

Re: Thanks To All

that crossed my mind but i could not think of a good way to state it. things like this happen all the time like the time i put the chain on the chainsaw backwards and could not understand why a newly sharpened chain would not cut. i even took it back to the guy who sharpened the chain.