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Blown head gasket vs. cracked block
Ok, folks when I got my '66 (inline 250) there was lots of white smoke coming out of the tailpipe that I chalked up to bad gas and a messy carb. However, after only 20 mi on it, I found the crankcase is down a couple quarts and the rad is dry. Is there a good way to determine if I just need to replace the head gasket or if the engine is toast (cracked block)? The compression is pretty good and reasonably uniform across the cylinders. Ideas? Thanks!
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Re: Blown head gasket vs. cracked block
Sounds like a crack in the head somewhere . Good compression would indicate that the gasket is good. I have seen some cracks in the exhaust ports that act just as you describe. The oil use is really extreme and I am surprised that the smoke is not blue. This could be caused by lots of things. Bummer bummer, bummer. When I get back from the woods I will pm you. BC .
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Re: Blown head gasket vs. cracked block
Howdy, Vern.
Good to see ya. IME, the weak spot prone to freeze damage on the I-6 is external, just above the freeze plug (ironically) under the manifolds. I've seen 4 or 5 with the same failure. At least two were 292's....but I do remember a 250/230 or two with the same pattern. But that's not the only way to crack a block, as we all know. It doesn't take much compression to puke out all yer coolant. I'm thinkin if you warmed it up a little, you could pick up an internal crack (or head gasket leak) with a compression guage in the bleed down mode. You could also pull your thermostat and housing and top it off with coolant (water) and start her up and let it warm up.....and watch for a constant stream of bubbles (or a gusher). Maybe. Good luck and keep us in the loop. |
Re: Blown head gasket vs. cracked block
Rock Driller, thanks for your help! My mechanical skills aren't the best so, bear with me here. I did run a block test and it was negative. The bumper next to the tail pipe is black, so it seems to be burning lots of oil. Given that the engine is really messy and leaking oil all over the place, I was thinking about buying a gasket set and replacing the head gasket. Would that be a potential fix or should I run other tests first? Much appreciated!
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Re: Blown head gasket vs. cracked block
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There is always a risk that a bad gasket could fill up a cylinder with coolant after you shut off the engine and possibly cause severe breakage the next time you turn the engine over and it can't compress the fluid. If the engine still runs and starts okay you can guess that the leak could be going into the exhaust port as suggested already. A head gasket leak on the compression side could also put a puddle on the ground and pressurize your radiator blowing coolant out the cap, possibly blowing a weak hose and or cause the water pump shaft to start leaking. Depending on what you know about the engine history you could just have the head gasket/head replacement done but in my experience it makes sense to at least do rings and bearings along with that if not an even more complete rebuild. Or maybe you have access to another good dropin engine. |
Re: Blown head gasket vs. cracked block
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Pulling an I-6 and doing it on the stand is usually as attractive as leaning over (or jumping in) and doing the job that way. That being said,....if you do pull it to change the head gskt.... and find out that the head gskt was the problem.....then that gives you something constructive to do with the rest of your gasket set. (and you might find other things that need attention). But then you have to make a pile of other hard decisions.....like (but not limited to)....do I pressure wash the engine bay....? and while it's so clean and accessible ....do I paint it...? Should I order some grommets...and so on, and on and on...blah blah. Let me know what you decide... At least it's not yer D-Driver. |
Re: Blown head gasket vs. cracked block
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Sometimes you can get away with a budget rebuild such as saving your crank, cam, lifters, pistons, valve train, even the oil pump and water pump. If these parts are not excessively worn. you could possibly getaway with tank cleaning everything and put it back together with rings, bearings, gaskets and maybe valve guides. If you have not done this before and you like mechanical work just do a little research, ask for a little help here and you will do fine, it's easier than you might think. It will be fun to do!:goodluck:Hope it goes well. |
Re: Blown head gasket vs. cracked block
YeeeeHaww
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Re: Blown head gasket vs. cracked block
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:ahhhh: |
Re: Blown head gasket vs. cracked block
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Ah, a mechanic family member says I'm crazy and need to drop in a crate 350 with fuel injection. I kinda like the put-put 250 with the manual pull choke... hopefully I can salvage it. Unfortunately, I don't know much about the engine other than it's not the original. The guy I bought it from didn't seem to know too much about it. I think the casting number puts it between '67 and '71. Is it possible to replace the rings without pulling the engine? It seems like replacing the rings wouldn't be too bad, but could be a nightmare if it's still in the engine bay? How about those rebuilt kits that actually include new pistons and rings? |
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