Head gasket replacement: What did I do wrong?

DSpieg

True Classic
Breaking news: Gene Cooley's idea that the water pump may have been vapor-locked, might have been the answer.

After Carl left I thought about the situation some more and it seemed unlikely to me the radiator is bad, so maybe the water pump wasn't pumping? I disconnected the bypass hose from the top of the water pump and poured a little coolant into it to try to 'prime' the pump, then reconnected the hose and started the engine. As before it idled up to maybe 115C, but this time I revved the engine to about 2000 rpm and held it there. The coolant temp steadied, and all of a sudden it dropped down to maybe 90C and stayed there. At about the same time, a slight whine from near the water pump disappeared. I'm guessing that bit of activity broke the vapor lock and finally got the coolant flowing again.

Next step: Reinstall thermostat, and retest/drive. Will probably have to wait until next weekend for what I sincerely hope will be the final chapter in this embarrassing story.
 

carl

True Classic
The whining was your dog(s). Hope you got the problem but a 50 year old radiator is still going to be unhealthy. As we discussed, get that spare rad refurbished.
 

DSpieg

True Classic
Spare radiator turns out to be for a different 850 model (maybe a sedan?) - top pipe is in a different location. So not going to refurb it. As for the whining: I have real dogs, they don't whine, they BARK (molto giusto, fortissimo).
 

DSpieg

True Classic
Weekend update: Thermostat back in, drove the car about 30 miles today. Temperature stable at around 110-115C (interpolating between the 90C and 130C marks, there are none in between!). Based on almost 10 years of experience with this car, that's about 10-15C too high for the conditions, so I'm beginning to believe the 'radiator needs renovation' crowd. In the meantime I've put in a bottle of Prestone radiator cleaner, and per the directions will drive the car about 3 hours with that stuff (and plain water) in the system, then will drain and refill with standard 50/50 coolant mix. This will be an interesting test of the Prestone chemical - will it have any effect? Place your bets........
 

gene cooley

Autocrosser
You probably have already done this but don't forget to clean the outside of the radiator. The fan will pull oil vapor from the engine compartment and deposit it on the fan side of the rad. Then the oil starts to collect dust and it can block the fins.
If this happens the temp will rise like you are seeing now.
 

DSpieg

True Classic
Thanks Gene, have done that several times in the past few years, including recently. Basically I spray the radiator and fan with Gunk, then hose it off.
 

gene cooley

Autocrosser
Thanks Gene, have done that several times in the past few years, including recently. Basically I spray the radiator and fan with Gunk, then hose it off.
Time for a laser thermometer.
Is the lower radiator hose still cold?
You said that you reinstalled the distributor where it was, but did you check the timing with a light?
If the temp is getting to 130/260 for any length of time you should have seen some indication of it being that hot.
The head will crack if you spent too much time at that temp--I'd rather not say how I know that...
Drain the coolant and pull the lower hose, then stick a hose in the top of the radiator and see what comes out the bottom.
I do have an extra radiator if you have a problem there. I'm in Richmond, (sorry I meant just outside of Richmond), if you you find you need a radiator.
 

DSpieg

True Classic
Gene: I do have a laser thermometer, checked temps yesterday once, the upper hose showed 140C and lower was around 80C at that moment - in other words the lower hose was certainly warmer than ambient, but cooler than the top hose (which I think is how it should be).
I rechecked the timing last night, it was basically correct, but less stable than I remember it being in the past, it seemed to vary about +/- 5 degrees or so, still scratching my head about that. I haven't changed the distributor or the (Pertronix) trigger, don't know what could be causing the timing to wobble - thoughts?
Temp never got to 130C yesterday during my 45-minute drive in 85+ degree F ambient. As I wrote above, it stabilized at about 110-115C for the entire drive. I could probably live with that, but it's about 10C warmer than it ran in the past (for the nearly 10 years I've had the car).
After I've put another couple of hours on the motor, I will be pulling the lower radiator hose, sticking a garden hose in the top of the radiator, and flushing out the Prestone cleaner. That should be instructive.
Thanks for letting me know about your spare radiator, I'll keep that in my back pocket.
 

NEG

True Classic
Timing that’s moving about could indicate a worn distributor. Is there any side to side play in the distributor shaft?
 

DSpieg

True Classic
Nah, dizzy shaft feels pretty good, and it's the same distributor that was in the car prior to the head removal. The timing didn't move around then. Hmmm.....
 

gene cooley

Autocrosser
I'll check mine tomorrow, but a 60C drop through the radiator seems like a lot.
I think that points to restricted/slow flow somewhere in the system, most likely but not necessarily the radiator. Could be the pump, could be a restriction anywhere in the system.
 

gene cooley

Autocrosser
I ran mine at idle for about 20 minutes.
Got some confusing numbers that lead me to believe there's no thermostat.
Outside temp was 93F.
Temp guage read about 70C.
Thermostat housing 67C (+/- 5C)
Top of rad was 62C at fluid level.
Bottom of rad was 50C beside outlet.
Pump housing was suprising, inlet/housing/outlet were in the 70C range. Fan heating outside of pump?
EDIT/NOTE: FAN SHOULD BE COOLING PUMP, NOT SURE WHAT'S HAPPENING HERE. PUMP TEMPS ARE CORRECT.
Bypass hose fitting and temp sensor were 70C, agreed with temp guage.
A couple of shots on the block were 55C (+/-). I think this is the actual temp inside the water pump.
Hope you can make something of this.
 
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DSpieg

True Classic
Now those are some odd numbers! For a 93F day, hard to believe your coolant never got above 70C. Will admit I was pretty hasty taking my own temp readings when Carl was here, I will try again this weekend with a little more scientific rigor 😬
 

DSpieg

True Classic
Funny you should ask, Gene. I just finished putting the Prestone-mandated 3 hrs. of driving on their coolant cleaner yesterday, flushed out the system with fresh water late last night, and refilled with the standard 50/50 coolant/distilled water mix. Just now got back from a successful test drive, and took another set of (hopefully definitive) IR thermometer readings.
Good news! The Prestone coolant flush actually worked - it dropped average gauge temp from the June-July 105-110C to the much more comfortable 'old normal' of about 100C. Here are the IR thermometer readings (averaged from two sets of readings):

Outside air temp: 80F
Top of radiator (metal): 179F
Radiator cap: 109F
Upper radiator hose: 163F
Lower radiator hose: 153F
Thermostat housing: 154F
Top of cylinder head: 165F

I'd also point out that on first startup this afternoon the temp gauge started its fast upward climb, reaching about 120C, but when I quickly opened the heater valve and then pinched the water pump bypass hose a couple of times, the temp dropped right down to the correct 100C and stayed there through the entire 15-minute drive. Makes me believe that the water pump is indeed prone to vapor lock after coolant replacement.

Thanks to everyone for the advice and emotional support! I believe we've got this one licked.
Dave S
 

kmead

Glutton for punishment
Funny you should ask, Gene. I just finished putting the Prestone-mandated 3 hrs. of driving on their coolant cleaner yesterday, flushed out the system with fresh water late last night, and refilled with the standard 50/50 coolant/distilled water mix. Just now got back from a successful test drive, and took another set of (hopefully definitive) IR thermometer readings.
Good news! The Prestone coolant flush actually worked - it dropped average gauge temp from the June-July 105-110C to the much more comfortable 'old normal' of about 100C. Here are the IR thermometer readings (averaged from two sets of readings):

Outside air temp: 80F
Top of radiator (metal): 179F
Radiator cap: 109F
Upper radiator hose: 163F
Lower radiator hose: 153F
Thermostat housing: 154F
Top of cylinder head: 165F

I'd also point out that on first startup this afternoon the temp gauge started its fast upward climb, reaching about 120C, but when I quickly opened the heater valve and then pinched the water pump bypass hose a couple of times, the temp dropped right down to the correct 100C and stayed there through the entire 15-minute drive. Makes me believe that the water pump is indeed prone to vapor lock after coolant replacement.

Thanks to everyone for the advice and emotional support! I believe we've got this one licked.
Dave S
Congrats!
 

gene cooley

Autocrosser
Funny you should ask, Gene. I just finished putting the Prestone-mandated 3 hrs. of driving on their coolant cleaner yesterday, flushed out the system with fresh water late last night, and refilled with the standard 50/50 coolant/distilled water mix. Just now got back from a successful test drive, and took another set of (hopefully definitive) IR thermometer readings.
Good news! The Prestone coolant flush actually worked - it dropped average gauge temp from the June-July 105-110C to the much more comfortable 'old normal' of about 100C. Here are the IR thermometer readings (averaged from two sets of readings):

Outside air temp: 80F
Top of radiator (metal): 179F
Radiator cap: 109F
Upper radiator hose: 163F
Lower radiator hose: 153F
Thermostat housing: 154F
Top of cylinder head: 165F

I'd also point out that on first startup this afternoon the temp gauge started its fast upward climb, reaching about 120C, but when I quickly opened the heater valve and then pinched the water pump bypass hose a couple of times, the temp dropped right down to the correct 100C and stayed there through the entire 15-minute drive. Makes me believe that the water pump is indeed prone to vapor lock after coolant replacement.

Thanks to everyone for the advice and emotional support! I believe we've got this one licked.
Dave S

Just keep an eye on the temp for a while, but it sounds like you found the problem.
Good work....
 
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