well, the boiling over problem "healed" itself a month ago while I was still working through the many good suggestions posted here...

I'm now thinking that ray was right from the very beginning...accumulated, loose crud, maybe blocking the radiator tubes?..

I'm going to do another flush this week to see if the problem stays fixed...I drained the system today and the three-week-old coolant is looking a little dirty already...

at least I verified that there hasn't been a thermostat installed...


epi

well, I finally had a chance to try looking for bubbles down the radiator neck while one of my sons cranked the engine, having first removed all but one spark plug...moved through all six without any bubbles appearing...

btw, since the problem corrected itself a while back, there hasn't been any foaming, boiling over, oil or tan-colored foam, etc...

either the water pump packing nut finally sealed adequately (thanks, chip) or the radiator blockage cleared enough (thanks, ray)...I did do a system flush a couple weeks ago as routine maintenance...


epi

When the problem comes back, and unfortunately it will you will have a good idea what to do.

Another coverup is to add an overflow tank. All you need is a cap that seals the radiator neck and a hose from the end of the overflow tube to the bottom of the tank. Make sure that the tank is well vented so the air can escape. The tank should hold about a quart of fluid. Only fill to bottom of the tank or less when cold. When you shut off the engine or return to idle from sustained higher speed watch the tank (if it is a clear, or see through plastic or glass). You will see the tank filling and then gas bubbles. When the engine cools the coolant will be drawn back into the engine. Yes is works for non-pressurized but sealed systems too.

chip,

thanks, chip...yes, I know that the problem will ultimately rear its ugly head again...but in the meantime, I'll continue running through the various good suggestions posted here to see if I can locate the source of the problem, or at least more clues...

I think rather than install an overflow tank (wasn't an option, was it?), I'll go ahead and replace the radiator core & hoses, and rebuild the water pump (there aren't any packing nut threads showing)...

any suggestions what parts I'll need for that pump repacking & where to purchase?..


epi

Gary Wallace sells water pump packing. I would try that before doing all the other stuff, unless you have done that already (re-pack the pump). Usually you will see a dripping of coolant after shutting down the engine if the re-packing is needed,a small drip is not unusual and usually just requires a couple or pulls on the packing nut to fix if you have an ample amount of threads showing. I don't know if any of the other Shade trees are useing "O" rings or not, maybe we can get some comments here about that.
Is there any literature out there about re-packing the Chevrolet water pumps, and useing a packing hook? I learned this years ago when I was a teenager driving a Model "A" Fourd.

mack,

thanks for the reply...no, I don't see any dampness whatsoever around the shaft...I'm just following through with chip's suggestion that air may be sucking through this packing while operating...

also, the core's at least 35 years old, if not original and previously, ray correctly pointed out that the roadster only went 500 miles during most of that period...

so, I'm slowly going through all the options and hoping it's not internal...as I recently posted, it hasn't boiled over in the past few months, and I try to put 5-15 miles on it each week to keep things moving...


epi

Maybe you just got it "broke to the saddle" and it is going to behave!

mack,

I wish I thought that was going to be the case...


epi

I ran a compression test today and had these readings...first number is highest reading, followed by pressure held steady (except cylinder #5) after a few minutes:

1 67# 65#
2 65# 60#
3 68# 57#
4 60# 60#
5 55# 45# and continued to slowly bleed down
6 65# 60#

they were all lower than I would have expected and #5 is a concern, of course...comments?..


epi

Kepi,
Looks like a couple of leaking exhaust valves. It can be fixed but requires removing the head. May be able to just lap them if the faces are not eaten too much. If you plan to drive it a lot I would fix it now. If only occasionally I might live with it a while and checking every now and then to see if it gets too much worse.

chip,

how much is "drive it a lot"?..and "much worse"?..

I drive it no more than fifteen miles at a stretch, but I try to drive it at least once a week, sometimes just up the road & back (a mile or so)...


epi