61 270hp cooling problem

[Joe L.]

Re: 61 270hp cooling problem

I hate to suggest this as it is a rather scary thought but you might check for bubbles in the coolant with the cap off as it might suggest a blown head gasket.

https://tinyurl.com/combustiongastester

I tested mine fearing a blown head gasket or cracked or warped heads and thank goodness, the fluid stayed blue! It is also a negative reading when you squeeze the bulb and you can't get it to expand.

Keith------


Yes, it would be a good idea to run this test which is called a "block test". A tester and fluid can also be purchased at Harbor Freight and their tester is virtually identical to the one pictured. Also, make sure to buy the smallest quantity of fluid that you can as this fluid is not really long-lived. By the time one uses it for the second time, the fluid will have degraded.

[Joe S.]

Re: 61 270hp cooling problem

Thanks for the suggestions. The cap does hold pressure since the top hose is hot and very hard when it is up to operating temp. I will try feeling for circulation. The top of the radiator core is very hot to the touch when running and the bottom is cool so I assume I have a free flowing radiator. Its a new DeWitt direct fit. I have been trying to avoid pulling the intake, but may have to so I can block that exhaust passage. We installed the engine before body drop so as not to risk any paint damage. Pulling the intake comes with some level of risk.

[Keith R.]

Re: 61 270hp cooling problem

Have you had the radiator cap tested to see if it is accurate?

[Richard M.]

Re: 61 270hp cooling problem

If combustion gasses are in the coolant, the block tester method as Joe, et al described is the best diagnostic tool. I suspect that's not your issue as your lower radiator hose would've likely blown off the water pump by now, and/or with the radiator cap off it would probably volcano like this after a shut down when normalized.....

You really have to use a IR gun to get a baseline measurement to verify your Temp Sender. I've done extensive testing of various sending units and it's a pet peeve of mine that we have so much trouble with such a simple part. My sender of choice is the Napa TS6469.
It's the ONLY one out there that actually had a ohms/temperature spec at a recognizable range..... 72-88 ohms at 210*

See Senders #'s 10 & 11 2nd page. Even NOS Delcos are junk.

Rich
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[Joe S.]

Re: 61 270hp cooling problem

Thanks one and all for the suggestions. I did get a IR gun and the sending unit seems to be ok. I think I found the problem. I spoke to the Paragon Tech guys and they made two suggestions. One was non-ethanol gas, not available in the DC metro area, and the other was timing. The timing was set a little more advanced than the factory spec, according to the scale, but the tech guy said that one should ignore that and advance until it pinged or struggled against the starter on a warmed up start and then back it off a little. What the heck? I got out my ancient Craftsman timing light and started advancing it a little at a time. After about the 5th adjustment, it ran much better and the gauge stayed at 180! By this time I had left the timing scale way behind and it still had no ping and warm start struggle. I will continue the process. Given all of this it seems to me that the distributor must be in a tooth off. Does anyone have any thoughts about just continuing to advance until I find the sweet spot vs pulling the distributor and starting over? With the electronic ignition, it shouldn't be necessary to retime once things are working correctly.

[Frank D.]

Re: 61 270hp cooling problem

IIRC the timing tab should support 16* or more of static timing, each tic being 2*. No amount of acceptable advance should take you off the tab, so yes you may have something wrong with the distributor install OR your timing light is on the wrong plug wire.

[Terry D.]

Re: 61 270hp cooling problem

If it was me I would pull the distributor and get it right. Not sure I understand your last statement, once the distributor is in the right tooth you will still have to time it and most likely will find it is in specs