Help diagnosing an engine problem

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Nov 8, 2004 | 12:26 PM

#16

StarFox

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Joined: Feb 2004

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From: Raleigh, NC

Since the problem goes away, or nearly so at operating temp, I don't see how it might be a short in the wires. I would think that it would short all the time regardless of the engine temp. The crack idea in the manifold is interesting, but a much bigger problem than shorted wires!

Nov 8, 2004 | 05:16 PM

#17

Jag Red 54

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Joined: Oct 2002

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From: Valley Center, CA

Randy Jack, in the cap you can look underneth to varify that all the studs look uniform. If one is burnt off or broken, then it will be obvious by discoloration. On the "running it in the dark idea," I only said exhaust because that was where my problem ended up being. But if a wire is shorting, no matter what the cause, then you will see the sparks in the dark. Also, are the caps snapping as you puish them onto the spark plugs? Sometimes they don't make good contact. Good luck, John

Nov 9, 2004 | 06:05 AM

#18

GreatNorthWoods

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Joined: Apr 2002

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From: Littleton, New Hampshire

Quote:

Originally Posted by Randy Jack

Ed - Vern - An engine guy I know also mentioned the crack in the head idea. I really didn't want to hear that! I'm trying to rule out everything else before I have to tear my engine down. If that works out to be the problem, I assume that magnafluxing the head is how to find a crack and then it can be welded and resurfaced? Or would you just replace the head? .

Randy,

I just replaced the head on mine. I think that is probably cheaper than trying to repair the old one unless you have some exotic or irreplacable head.

Vern

Nov 9, 2004 | 09:29 AM

#19

imlowr2

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Joined: Apr 2004

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From: Santa Clarita

As far as replacing the heads, I'm with North Woods. If the head has a crack, it is repairable but I would just replace the head with a new/ rebuilt one. There are places that will exchange your head for a good one. I wouldn't rely on welding it, etc. As far as heads, unless you had them shaved or custom work done, they will fit the same model engine (289, 302, 351, etc.). Just for curiousity, try Jag Red's idea of opening the hood at night and checking for sparks. I've done that a few times. It works out nice around Christmas when your engine compartment looks like a Christmas tree ! (smile)....

Nov 9, 2004 | 09:38 AM

#20

seaves46

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Joined: Mar 2004

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From: australia

Randy, are you loosing engine coolant, or getting excessive water vapour from your exhaust ? Also run the engine at idle when cold with the radiator cap removed and look for small bubbles in the coolant. all signs of a blown head gasket or cracked head. Also most radiator shops should be able to preasure test your cooling system , if your cooling system preasure test passes this should rule out cracked heads or blown gaskets.
Scott.

Nov 9, 2004 | 09:49 AM

#21

Randy Jack

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From: Riverside, So Cal

John - Thanks, I'll take a look under the cap. I'll run it after dark tonite to check out any light shows.
Ed, Vern - Point taken, swapping out the head would be easier and more reliable than repairing. These are 351C 2V heads, not ported and easy to find. (I still hope that ain't it!)
Scott - No, not losing any coolant. No bubbles. No excessive vapor in exhaust, just condensation that blows out after starting.

Nov 9, 2004 | 06:06 PM

#22

oldsenile

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Joined: Aug 2004

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Don't clean and regap plugs, replace them. I've seen bad ones right out of the box, look ok but bad

Nov 9, 2004 | 10:10 PM

#23

wademo

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Joined: Nov 2003

Posts: 65

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From: Paulden, Arizona

My money is on the vacuum leak theory. Did you try shooting the propane into a valve cover when the miss is at its' worst? Any vacuum ports on that intake runner? I have also seen cracked intake manifolds ( cast iron ).You need to be careful, but sometimes a shot of carb or brake cleaner instead of propane gets a better reaction, even in the valve cover, just remember to change your oil. Good luck, Wademo