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Coolant Loss

I was driving the car on Friday night and all was well until I had been driving about 30 miles, and then the temperature began to creep back up again. After the car cooled off, I found the overflow tank full, but the radiator down 4 to 5 inches. There's definitely some nasty stuff mixing in with the coolant, but I can't tell if that is something that is recent, or the product of 46 years of detritus. My gut is I have a small head gasket leak that only rears its head when the engine has been running for some time. I'll try retorquing the head again and see if that helps things out. Otherwise, I'll likely have to change the head gasket again. Like so many other things I've done on the Sprite, I usually end up doing a better job the second time around than my first attempt, so I'm not overly pressed if I have to go this route.
 
Payen Black! Nothing else will do.
 
I did use the Payen gasket. I'm thinking my fault lay in the reassembly that I didn't secure the studs as well as I could have. We shall see. Having done the head gasket change once, I'm far less intimidated having to do it a second time around if my hunch proves to be correct. I'm hoping I'm wrong though and all I had was an air pocket in the system.
 
...and after over 50 miles of driving, the needle came nowhere near the "N" today, and all I did was put more coolant in.

Also, looked at another Mark IV Sprite today, but that's another topic for another thread.
 
I wouldn't tear into the head gasket again until I did a pressure test on you cooling system. You may have a pin hole somewhere that is letting air in when it should be sucking coolant out of the overflow tank and leaking as well but in small enough quantity that you aren't noticing it.

Kurt.
 
The problem I'm having with the pressure test is that none of the adapters in the Pittsburgh Tool kit that I ordered from Harbor Freight fit either the neck of the overflow bottle or the brass plug on the radiator itself. I'm thinking that I'm just going to have to treat the coolant like oil: Fill up the car with coolant and oil and top of the gas.
 
The overflow container should have a fairly standard cap. I sure would think that an HF kit should have that. Course maybe something that used to be standard isn't anymore. How about talking to the guys at the local auto parts store? Repair shop's?

Kurt.
 
One of the head bolts definitely loosened up, so I retorqued it this evening. We'll see if that puppy was the culprit.
 
I should have been checking in here more often. I've been having the same symptoms (drive the car 45+ minutes and the top third of the radiator empties itself into the overflow tank, temp soars, it doesn't suck anything back into the system as it cools. 1275 and a crossflow radiator, too.) for the last few, uh, years and finally took it apart (I needed to take another stab at degreeing in the cam anyway) over Xmas break and am just now getting it back together. The life of a high school science teacher, eh?

Anyway, here's what my Payen headgasket looked like when it came off:

Total blow-by from #2 and #3 into the coolant hole between them. I checked the head with a straightedge and it was a bit warped, .006 clearance in the middle. I stripped it and have had it shaved and will be getting it back on the road this week.

There's one more step if this one fails (other than stripping the block to have it decked) and apparently there's a competition head gasket sold by Seven Enterprises which is supposed to be THE thing. A mechanic friend of mine found it to be the only material to stop leaks on a troublesome Jag XK, so down the road (so to speak) there's that if necessary.

HTH, but it'd sure be nice if it's just that loose head nut!
 
I should have been checking in here more often. I've been having the same symptoms (drive the car 45+ minutes and the top third of the radiator empties itself into the overflow tank, temp soars, it doesn't suck anything back into the system as it cools. 1275 and a crossflow radiator, too.) for the last few, uh, years and finally took it apart (I needed to take another stab at degreeing in the cam anyway) over Xmas break and am just now getting it back together. The life of a high school science teacher, eh?

Anyway, here's what my Payen headgasket looked like when it came off:

Total blow-by from #2 and #3 into the coolant hole between them. I checked the head with a straightedge and it was a bit warped, .006 clearance in the middle. I stripped it and have had it shaved and will be getting it back on the road this week.

There's one more step if this one fails (other than stripping the block to have it decked) and apparently there's a competition head gasket sold by Seven Enterprises which is supposed to be THE thing. A mechanic friend of mine found it to be the only material to stop leaks on a troublesome Jag XK, so down the road (so to speak) there's that if necessary.

HTH, but it'd sure be nice if it's just that loose head nut!

You need a Payen composite BLACK head gasket. You have a metal sandwich gasket that are notorious for problems. You also need to remove the brass plug that is in the center and replace it with a threaded plug before the head gets surfaced.
Kurt.
 
I think the part number is BK450 there is another black payen gasket, but this is the one I've had success with.
 
A happy accident happened tonight while working on the car:

I was putting a new valve cover and gasket on the motor to see if I could stop finally stop the oil leak between cylinders 3 & 4 on the passenger side. While getting the valve cover straight before I tightened up the bolts, I accidentally leaned on the heater return hose. When I did that, I was greeted by the sound of air bubbles escaping. So I tried it again, just to see if I wasn't imagining this. Sure enough, more air bubbles. I checked the passenger side of the core and pushed on the hose. Nothing. So, I cranked down the hose clamps. Air bubble noise stopped. What is the saying? When you have a problem, the most likely culprit is the most obvious one...

I'm working on my MacGyver pressure tester to see if any other leaks pop up. I'm hoping to have that operational tomorrow.
 
20 miles Friday night and then another 40 today in 90 degree temperatures, and the needle sat in its usual spot between the "C" and the "N" the whole time, even when we stopped for traffic lights. It looks like I finally got this particular problem licked.

As a side benefit, when I replaced the valve cover, I readjusted the valves, and this time I did a much better job than I had previously. The "smokescreen" I used to have at the bottom of long downgrades when I got back in the gas has basically disappeared.
 
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