1967 Overheating Issue

[Snibbor]

Bruce,

I just checked and the coolant is down probably 4" from the top. Have not started it since yesterday. But it can't be normal to go from overnight cool to 1/4 from max temp idling for 5 minutes.

[Snibbor]

Hi Bruce,

It sat overnight. And I just checked the coolant level and I'd guess it probably 4-5" below topping out. It cannot be right that it goes to 1/4 from max on the temp guage when idling for a couple of minutes. I  understand the rpms when driving and how that is better but it quite literally spews coolant which it NOT right after sitting for a couple of minutes.

[Snibbor]

Bruce,

Just checked and after an overnight/all day rest the coolant looks to be down 4-5"...

[The Tassie Devil(le)]

G'day James,

Sounds like you need to get the coolant condition checked, and analysed for things like combustion contaminants, to see if there is any ingress of the cylinder combustion process in the coolant.

Short of that, there is not much I can add, as internet diagnoses is really difficult.

I suppose you have done a Compression test, and the compression leak down test on each individual cylinder, there you put compressed air into each cylinder, with the valves for that cylinder closed, and then listen for bubbles popping in the radiator to indicate a gasket leak into the coolant passages.   This way, without the engine running, all other noises are out of the equation, apart from leaking valves where this noise will be heard at the Carby or Exhaust, and Sump as the air bleeds past the piston rings.

Plus, failing everything else, what are the actual temperatures at various parts of the system, using an Infrared temperature measuring device.

Lastly, I take it that the '67 Cadillac uses a cross-flow radiator, or you wouldn't be able to see the level so low.   My Ranchero has a Cross-flow radiator, and I couldn't believe it was that low when cold, but, yes it was.   I fill it up, and the next day, after running that is, the level is back there.   The only changes from factory is that I replaced the 302 with a 351 and kept the original radiator.

Surely there is someone out there with another '67 that hasn't been altered that can look into their radiator and divulge their coolant level when cold.

Bruce.

 

[Snibbor]

Bruce,

The radiator was checked out with an infrared device at 190 degrees and I assure you it was flushed and checked and has not pockets or contaminants.

[The Tassie Devil(le)]

James,

My reference to combustion contaminants was with regard to the transfer of hydrocarbons, and stuff from burning petrol, and oil, that would be transferred to the cooling system via the cylinder pressures forcing the exhaust gasses through a possible leak in the head gasket, which could indicate a blown head gasket.   Remember that gaskets can leak both ways, one way under low pressure, and the other direction under high pressure.

Now, at what temperatures are you having troubles with.   190 isn't all that bad, especially if you are running a 195 degree Thermostat.

As water boils at 212 degrees F, and with a pressurised system of say, 10 Lbs, then your coolant is not going to start to boil until it reaches 232F.   For every 1 Lb of cap pressure, the boiling point of water rises 2 Degrees.   

Really sounds to me like you are looking for something that isn't there, especially for a 1967 system.

Using the Infrared device, what is the hottest the system gets?   (1) at the thermostat housing, (2)   At the top of the radiator?   (3)  At the bottom of the radiator (Tank or radiator hose)?

Remember that these engines are not to be compared to new ones, and should be regarded as basic systems.

Bruce.

[Snibbor]

Thanks Bruce. Great information.

[Snibbor]

Bruce,

Opinion on Watterwetter additive? Aux fan for radiator?

[skinny_tom]

Is your fan direct-driven? Are your belts tight? Is you fan clutch, if equipped, in need of replacement?

[Snibbor]

Going to check the fan clutch.

[Mike Baillargeon #15848]

I popped the hood on my 1966 Fleetwood today to check coolant level in the radiator....I never check this but I thought I'd take a look because of your problem...

Coolant level is down 4" from the top....I haven't driven the car in a week so all is cool....Bruce may be on to something....this is the operating level of coolant...

I think my motor is the same as your 1967...

Mike

[Snibbor]

Thanks Mike.

[Snibbor]

I have also noticed that it is  dieseling or has run-on after the engine is cut off...could this be a sign of head trouble?....too hot/compression is high?

[Snibbor]

By GOLLY with a LOTTA help from this forum and the right guy we found the solution. New fan clutch. We stuck a magazine in the fan and it barely shredded a page. He also did a CO2 test with some solution atop the radiator opening and there was NO discoloration! so that (apparently) rules out a blown head gasket. Whew!
Thanx again for all the advice.

[The Tassie Devil(le)]

G'day James,

Great news.

As for dieseling, this happens when the throttle plates in the carby are not closing sufficiently to stop the air flowing into the engine.

This is one reason that makers installed anti-dieseling solenoids to the engines.   What these did was when set up, and the ignition turned on, the plunger was moved by an electromagnet and this opened the carby throttle plates to give the correct idle speed.   When the ignition is turned off, the plunger retracts, allowing the throttle plates to completely shut.

The adjustment is set at idle, using the plunger as the throttle stop.

If there is any carbon-buildup in the combustion chamber, this gets hot due to the engine running, and these hot spots can act as a secondary ignition point to keep the engine running.   The Anti-dieseling Valve stops the air flow when the ignition is off.

Bruce.  

[TD Alex]

All these responses are very systematic and very logical.  I will offer my experince with coolant loss that took me months to discover and now going for a rebuild on engine.  Maybe I can save you the heartache and money I went thru.  The timing cover had a small crack on the top and was leeking minor amount of fluid.  To the unfamiliar it was not found.  Once the crack opened up enough to be noticeable it was discovered. I frantically looked for the repalcement part.  No longer manufactured and each year from '65-'67 only fits that year.  BUYER BEWARE OF WHERE YOU BUY THE PART!!!!!

It started a perfect storm of events.  From the company I bought the suppusoed "reconditioned" part from to the mechanic with all his experince caused me to spend thousands of dollars.  All parties involved pointing fingers but me paying.

Check the timing cover and I bet a dollar to a hole in a doughnut somewhere it is leaking.  If Im wrong?  Be happy to buy you a doughnut.  TD

[Snibbor]

TD,

Good info. I'll mention it if the new fan clutch turns out to be a "dud".....

[Snibbor]

Installed he new Fan Clutch yesterday. As per usual the part was a little too long (the clutch mandrel) so I had to shim the radiator forward a little to accommodate. I know. Sounds strange but bare with me. He suggested that I put a hard foam piece in the area boxed in red (see pic). That would help with the air flow. Please review the picture of what I am talking about and let me know if this would help. Thanx!IMG_2888 (2).pdf

[dn010]

I am dealing with a bad clutch fan in a 94 Jeep right now. It will overheat if it sits idling. Take it down the road and the needle will move from 210+ down to 180 in less than a minute. As others have been telling you in your auxiliary fan thread, it should be the same for you regardless of the fan - driving at highway speeds should be enough to keep the engine cool and if you're still overheating driving at these speeds, I wouldn't get my hopes up with the new fan. I hate to be pessimistic and I really do hope the fan works out for you but I just don't see that being the issue.

[Snibbor]

Thanks for the note Dan. Yea. I'm thinking the same thing. If the following does not fix the overheating issue I don't know what to do:

-Newly flushed/pressure tested radiator
-New Thermostat
-New fan clutch
-Confirmed no issue with head gaskets (with CO2 check on radiator)
-Confirmed no issue with timing cover (crack)
-New radiator cap