Engine problem help
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Cross-Country
Joined: Oct 2020
Posts: 52
Likes: 9
From: UT
Engine problem help
I have a 78 with a 302 that was freshly rebuilt. I just finished the cam break in a few days ago and I’ve now noticed a pretty bad miss and some white smoke out of the exhaust. I checked the plugs and all were fine except for cylinders 3 and 4. The plug on 3 was fouled and the plug on 4 was wet. Swapping the plugs did not change anything. I removed the valve cover and started the engine and could visibly see the valves opening and closing. The rockers are still tight as well. What should my next steps be?
Cargo Master
Joined: Aug 2003
Posts: 3,263
Likes: 92
From: BC Canada
before you start tearing the engine down,
Perform a cylinder pressure test,
perform a cylinder leak down test.
If you have access to a scope, run a primary and secondary wave for on the sparks and a wave form on the injectors
Lets gather evidence rather than guesses..
Perform a cylinder pressure test,
perform a cylinder leak down test.
If you have access to a scope, run a primary and secondary wave for on the sparks and a wave form on the injectors
Lets gather evidence rather than guesses..
Fleet Mechanic
Joined: Feb 2022
Posts: 1,368
Likes: 705
This may sound gross, but it’s a good way to check as to whether or not you have a head gasket leak and coolant is coming out of the exhaust.
Run it for a little while, dab your finger on the end of the tailpipe and taste it. Yep, stick it on your tongue. If it’s sweet, there’s coolant present. Spit a few times and then go grab a beer and spit a few swigs out. Hopefully no one notices.
Run it for a little while, dab your finger on the end of the tailpipe and taste it. Yep, stick it on your tongue. If it’s sweet, there’s coolant present. Spit a few times and then go grab a beer and spit a few swigs out. Hopefully no one notices.
Hotshot
Joined: Feb 2004
Posts: 10,743
Likes: 2,587
From: The Shenandoah Valley
Sounds like a head gasket.
What kind did you use, what was the prep?
Also .... if you feel the urge to mess with a lifter, make sure the same lifters go back in the same lifter bores as they come out of. Should not need to, but "if".
What kind did you use, what was the prep?
Also .... if you feel the urge to mess with a lifter, make sure the same lifters go back in the same lifter bores as they come out of. Should not need to, but "if".
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Tuned
Joined: Jan 2021
Posts: 254
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From: Longview Texas
Your nose can tell you what is coming out the exhaust. Just smell the smoke, oil and coolant are obvious. Then you can figure your next step.
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Cross-Country
Joined: Oct 2020
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From: UT
Lead Driver
Joined: Oct 2018
Posts: 7,837
Likes: 2,343
Is there water in the oil or oil in the water? it should be drinking water a little if it's a gasket. could be an intake gasket, if it is you should have water in the oil .
Oil fouled plug or washed out ?
Antifreeze is murder on bearings, don't run it until you get this resolved. I always break in on pure water and run it a while before I add antifreeze just for times like this.
Oil fouled plug or washed out ?
Antifreeze is murder on bearings, don't run it until you get this resolved. I always break in on pure water and run it a while before I add antifreeze just for times like this.
Thread Starter
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Cross-Country
Joined: Oct 2020
Posts: 52
Likes: 9
From: UT
Is there water in the oil or oil in the water? it should be drinking water a little if it's a gasket. could be an intake gasket, if it is you should have water in the oil .
Oil fouled plug or washed out ?
Antifreeze is murder on bearings, don't run it until you get this resolved. I always break in on pure water and run it a while before I add antifreeze just for times like this.
Oil fouled plug or washed out ?
Antifreeze is murder on bearings, don't run it until you get this resolved. I always break in on pure water and run it a while before I add antifreeze just for times like this.
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Cross-Country
Joined: Oct 2020
Posts: 52
Likes: 9
From: UT
The heads are a set of GT40s that I bought from a friend. I was told they were recently redone and they looked good. They have new trick flow springs, seals and retainers and the valves were lapped in. They could be warped but I doubt it
Lead Driver
Joined: Oct 2018
Posts: 7,837
Likes: 2,343
What carb? you might be loading up on fuel. normally gas is black smoke but if you're dumping raw fuel it can make a mess.
Your oil might smell like gas. trying another carb would be a simple test if you have one.
Your oil might smell like gas. trying another carb would be a simple test if you have one.
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Cross-Country
Joined: Oct 2020
Posts: 52
Likes: 9
From: UT
I don’t have another carb to try. The carb on the engine is a brand new Brawler 650 with vacuum secondaries and an electric choke.