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Pre-ignition / starting problem. Ripping hair out.

Wes Harden said:
sounds good to me. I'd say your about as flushed as you can get, w/o power flush. this was after chemical treatment and warm up ?

Keep an Eye on your heater core for a little bit, it may spring a leak depending on how old it is.
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The full procedure went like this:

Flushed the entire system (and heater core) both directions with thermostat out using a garden hose (filtered water)
Installed 160 Thermostat
Filled system with filtered hose water and some Prestone radiator flush and cleaner.
Drove the vehicle at high RPM for around an hour, with multiple stops (running errands in town).
Total time with the cleaner in the system was 3 hours maybe.
Drained radiator
Sprayed off thermostat and radiator cap.
Blew air through heater core to flush hot water out of it to prevent shock from cold water.
Put a shop fan in the engine bay to motor to bring the temps down faster.
Hose flushed entire system and heater core both directions with hose.
Flushed entire system and heater core with distilled water.
Flushed overflow reservoir and siphoned empty.
Added concentrated antifreeze from one side of the system until I saw it coming out of the other side of the system (3 gallons).
Filled overflow to proper level with distilled.

Overflow jug, and heater core were just distilled water, plus I'm sure some distilled water remained in the block somewhere.

I guesstimate that this will result in maybe 70% antifreeze and 30% distilled water.
 
Ya, I was curious about the heater core. Should be less stress on it with low temps / low pressures. Just have to wait and see I guess.
 
yes they are never the stoutest component. Sometime after being disturbed they just give up. I always try match the heater core materiel to the rad material. IE brass for brass or alum for alum. Couple years ago I found brass for mine at Summit, couldn't find else where.
 
Wes Harden said:
yes they are never the stoutest component. Sometime after being disturbed they just give up. I always try match the heater core materiel to the rad material. IE brass for brass or alum for alum. Couple years ago I found brass for mine at Summit, couldn't find else where.
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Not a bad idea, keeping the materials the same. They should be made to be bullet proof. A friend had Dodge truck that had a heater core go out. Book time to change it was 18 hours.
 
yeah I have done to many ac evaps on 2010+ stuipduties, good thing I wasn't flat rate. I did get them down to one 9 hr shift after the first 5 or 6
 
tRustyK5 said:
A similar issue I had with my old Jimmy back in the day turned out to be the vacuum advance mechanism being sticky. My theory is that I'd shut it off at idle of course, so the vac advance would be adding timing. Then when the engine would be shut off the mechanism would be sticky enough to retain some of that advance, so then I'd try for the hot re-start and I'd get the same brutallly slow cranking. Once it sat long enough the mechanism would have enough time to slide back to the correct timing. I replaced the whole vacuum advance unit, thoroughly cleaned the guts of my distributor and never really had that issue again.
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I think it might have been a funky advance in the distributor, since I did have issues with the timing marks changing between hot and cold. I found some non-conductive lubricant that I plan to hit the distributor with:



Or maybe I should just leave it alone since the symptoms are gone. Or maybe I should install that $50 distributor rather than spending $15 to lube the old one. Or maybe lube the new one and install it and go back to a 195 thermostat... Hmmmm.
 
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take the rotor off and look at the fly weights and springs, doesn't need much lube. I have seen them rusted unmovable. Then the vacuum advance with your finger push the pivot point toward the vacuum can, watch for the backing plate to rotate smoothly. a little lube between the base and backing plate, little will go a long way.
 
Blue85 said:
Another real possibility is that the advance mechanism inside the distributor is sticking.
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78 GMC Jimmy said:
Maybe the mechanism was stuck, who knows. Something expands when hot and gets hung up maybe.
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That's what I was saying - they will always get some gunk in them because the vapors from hot engine oil can come up the shaft. As it cools, something shrinks enough so the springs eventually overcome the stick. It's basically periodic maintenance to clean and lube the advance mechanism.
78 GMC Jimmy said:
I think it might have been a funky advance in the distributor, since I did have issues with the timing marks changing between hot and cold. I found some non-conductive lubricant that I plan to hit the distributor with:
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Don't be afraid to put a little dielectric grease or even other stuff in there to keep it freed up and keep corrosion away. Heck, I had a buddy with a Bronco that would stall every time he ran through a puddle. He would pull the distributor cap and spray the whole inside liberally with WD-40 and it would fire right back up (I'm not suggesting that, just an example). Plus, as it moves freely you get more consistent timing as your VAC/RPM are changing.
 
Is the any reason not to SOAK the distributor base / vacuum advance with WD40? Is that going to cause any problems?
 
it will attract dirt and need attention sooner, more isn't always better
 
Lube and test, how will know what fixed it. Lube won't help a cranky pick up coil.
 
Wes Harden said:
Lube and test, how will know what fixed it. Lube won't help a cranky pick up coil.
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Replacing the coil a few steps back didn't help. But the changing timing readings make me suspect the mechanical or vacuum advance. More than once I would set the timing and then it would seem to be more advanced when checked later. The more I think about it, the more I think it must be a vacuum advance that is getting stuck when hot. Not sure though.
 
Pinging can be caused by carbon deposits (or any hot spots in the combustion chamber), not enough octane, engine is too hot, too much compression, or not enough fuel. There are also things that sound like pinging but aren't. If the timing is inconsistent and sometimes gives hard starts, that's definitely the place to keep working. Something with the advance mechanism. I suppose a worn distributor gear could also add some variation.
 
Go back to the part where you verified the timing marks. What did you insert to the spark plug hole to do this. It almost reads like you just waited for pressure to blow your finger off.
 
Blue85 said:
Go back to the part where you verified the timing marks. What did you insert to the spark plug hole to do this. It almost reads like you just waited for pressure to blow your finger off.
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I checked it and another mechanic did as well. Sticking stuff into the cylinder.
 
If you're really "giving up", you could put a crank trigger on it and install a digital ignition.
 
70jimmy said:
My thought is the springs in the dizzy have gotten weak, buy a spring kit and experiment. Dusting off the part of my brain that hasn't messed with HEI in many years.
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I tried lubing the old springs and weights.
Then I replaced the entire distributor.
Didn't help.
 
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