Head gasket replacement: What did I do wrong?

DSpieg

True Classic
Just finished replacing the head gasket on my '71 850 Spider (903cc). Had brought the head to a local machine shop recommended by Tim Rooney; shop determined the head was warped and they milled it about .015" (I think that's what the man said, it wasn't written on the receipt). I then installed a "reinforced" head gasket from Chris Obert, in the belief that the bit of extra thickness might compensate for the material removed from the head.

Finished reassembly yesterday and started the car, it fired right up and seemed to be running normally, but within a couple of minutes the coolant temp had already hit 130C and was still climbing, so I shut 'er down. There was the beginning of coolant boiling in the plastic reservoir.

Why isn't the new head gasket sealing on a freshly-milled head? I did everything by the book, torqued the head bolts very carefully to a final value of 39.6 ft.-lbs. (the highest value I've got in any of my service manuals; some show a lower final value of 36 ft.-lbs.).

Did I make a poor choice of head gaskets? I'm wondering if the one I bought might be intended for racing and needs stronger head bolts and higher torque.

For now the plan is to start over again, but use a standard OEM-type head gasket of Italian manufacturer I've had in my parts bin for a while. Thoughts and recommendations? Grazie.
 

kmead

Glutton for punishment
The dowels could be holding the head up is one possibility.

There could be a crack in the head which is allowing coolant past.

Do you have water in your oil or oil in your water?

Did you reinstall the thermostat facing the correct direction? Is the thermostat still good? Try removing the thermostat to see if it still behaves this way.
Water pump pulley tension correct?
Ignition timing returned to where it should be after having pulled the distributor?
Is it running lean? Could the mixture screw have been inadvertently adjusted?

Checking the simplest things first after removing so many other systems is always the better way rather than blowing away what may be perfectly good work.
 
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DSpieg

True Classic
Thanks the suggestions all.

- I did check the fit of the two dowels pretty carefully (one had been put back in the wrong hole by the machine shop), so probably not the cause.
- I cleaned up the head pretty well before I gave it to the shop, wouldn't they have seen a crack if there were one? Unfortunately I never checked for that.
- The thermostat is nearly new, it was working fine before I removed the head, as was the previous one that had been installed a month prior. I don't think it's the problem either, but I suppose it's possible and worth a check.
- Pretty sure I installed the T-stat correctly, but will verify. Bought this one and its predecessor from Matt Brannon (Midwest Bayless).
- After just a minute or two of running on fresh oil and fresh coolant, it should be easy to check for cross-contamination of the fluids, I will do that.
- Didn't touch the water pump belt, tension is fine. Didn't touch the mixture. I was extremely careful to mark the distributor and head and line up the rotor with the #1 cylinder mark before removing the dizzy, and reinstalled exactly as before. I'm confident the timing was good as the engine started right up and idled and revved nicely for the short time it was running.

I'll start by removing the thermostat and test-running again, that's easy enough. Will report back........
 

dnudelman

True Classic
I'm running a Napa thermostat, 170 degrees, its Arizona. Temp is right where it should be. I'm using a new MWB head gasket on an 817 engine. The radiator is a fresh rebuild done by a local shop.
 

DSpieg

True Classic
To answer Dan's question: The coolant temp climbed so fast that I assumed it was caused by combustion gases entering the coolant, rather than just normal engine warmup. TBD. Tonight I'll remove the thermostat and see what happens.
 

Jeff Stich

True Classic
...but within a couple of minutes the coolant temp had already hit 130C and was still climbing, so I shut 'er down.

130°C and still climbing? Was this reading from the gauge, or from an infrared-type thermal reader, or from some other method? 130°C is the max reading on the dashboard temperature gauge, so if the temp was still climbing after that, you pegged the gauge.
temp.jpg
 
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gene cooley

Autocrosser
Pull the small bypass/recirc/air bleed? hose from the top of the water pump and make sure the port is not blocked. It's possible your water pump is air locked.
 

petex19

True Classic
The dowels could be holding the head up is one possibility.

There could be a crack in the head which is allowing coolant past.

Do you have water in your oil or oil in your water?

Did you reinstall the thermostat facing the correct direction? Is the thermostat still good? Try removing the thermostat to see if it still behaves this way.
Water pump pulley tension correct?
Ignition timing returned to where it should be after having pulled the distributor?
Is it running lean? Could the mixture screw have been inadvertently adjusted?

Checking the simplest things first after removing so many other systems is always the better way rather than blowing away what may be perfectly good work.
Can the thermostat be installed in the wrong direction?
 

DSpieg

True Classic
Update: Not good. Removed the thermostat, same story, within a couple of minutes was at 130C, shut 'er off. Noticed that (as yesterday) the car ran and revved well until the gauge hit around 110C, then the idle started to stumble a little and slow down.
Also, no oil in coolant, BUT the oil on the dipstick (Valvoline VR-1 10W-50) seemed really thin, ran right off, so I guess that means coolant is in the oil.

I do have an IR thermometer but I have no reason to doubt the temp sender (new and matches the previous one) or the dash gauge. I believe the temps I'm seeing are real.

Gene, I pulled the hose off the bypass hose on top of the water pump and poked in there with a wire, there was no blockage, and there was some warm coolant there.

What now? Back to square one?
 
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kmead

Glutton for punishment
Update: Not good. Removed the thermostat, same story, within a couple of minutes was at 130C, shut 'er off. Noticed that (as yesterday) the car ran and revved well until the gauge hit around 110C, then the idle started to stumble a little and slow down.
Also, no oil in coolant, BUT the oil on the dipstick (Valvoline VR-1 10W-50) seemed really thin, ran right off, so I guess that means coolant is in the oil.

I do have an IR thermometer but I have no reason to doubt the temp sender (new and matches the previous one) or the dash gauge. I believe the temps I'm seeing are real.

Gene, I pulled the hose off the bypass hose on top of the water pump and poked in there with a wire, there was no blockage, and there was some warm coolant there.

What now? Back to square one?
Oil with coolant in it will look like a milk shake, not hot and thin.
Have you drained the oil to see what it looks like?

Is the radiator over pressurized? Have you checked the radiator for oil? It would be right on top in the neck. Is the overflow tank showing boiled coolant when running? The overflow tank should show considerable bubbling if there is significant bypass of exhaust gasses and or overheating.

What coolant are you running? Typical green or something else that might disguise itself in the oil?

The bypass hose is below the top of the radiator, coolant should come out in decent amounts, not just “some” warm coolant In the hoses.
 

DSpieg

True Classic
Thanks for mo bettuh tips, Karl and Carl. In order of appearance:

1) Will drain the oil to look for evidence of coolant.
2) No oil in top of radiator.
3) I think the coolant in the overflow tank was just on the verge of boiling, but I shut off the engine (both times) before that could really get going, so not sure about this.
4) Standard green universal Prestone or equivalent coolant. I learned a really hard lesson about orange Dex-Cool incompatibility on my previous X1/9, will never do THAT again!
5) Will do a compression test, great idea. Carl, if you're bored and would be willing to come over and help with that sometime this weekend, I'll figure out a way to make it worth your while :)
 
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