7.4 L29 trouble, need advice

[Elroy]

i have a 1996 K2500 sub w the 7.4 , it has died on me twice , once for a fuse that powers the computer and once for the crank sensor. i was towing a 5000 lb camper last weekend cross country and it died 2 hr from home

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, it cranks and sounds like it tries but wont start, i cant get the scanner to connect to the computer, i checked the fuse and it seems good, there is oil coming what looks like behind the starter, i suspect possibly a head gasket? i know when it died there was some noise, i looked down and saw the oil pressure drop, i dont know if that was due to the engine stopping or due to head gasket fail, i did shut off the key at that moment and then turned it back so i could steer off the highway, its at the AAA shop now, i will have then diagnose the problem , it has 220K on it, looking at crate motors and such, i see GM sells a "new" L29 for about $5,800, and they have a 502 version for about a grand more, i will post more when i know what im up against, looking for help/opinions about crate motor vs rebuild and 454 vs 502 , best price/where to buy if it comes to that, near chicago in the western suburbs,

 

[someotherguy]

You won't have oil leaking from a bad head gasket. From the area you mentioned it's likely going to be valve cover gasket or lower intake gasket (probably just the valve cover.) When the engine stops for whatever reason, oil pressure will drop off immediately. So unless you saw the pressure drop -before- the engine stopped, it's not something to worry about.

It should be determined why it died before you start looking at replacement engines.

Richard

 

[Elroy]

thats where im at now, the shop it was towed to will diagnose it for me and then we will see, when i say leaking oil, its not a small leak like a valve cover gasket, and it didnt leak there before it died

 

[someotherguy]

Oil pressure sending unit may have sprung a bad leak or come apart, though on the 7.4 it sits straight up and on the driver's side top/rear of the block, so I'd expect it to come down on that side rather than passenger.

Head gasket failure doesn't spew oil. Valve cover gasket will leak a lot of the cover came loose or the gasket failed; these use a rubber O-ring style that sits in a groove in the cover. Even brand new ones can be tricky to make them fit correctly while installing as they often aren't a 100% direct fit and will try to pop out of the groove. If you had high crankcase pressure due to say a clogged PCV valve it might have blown the gasket out.

Richard

 

[Christian Steffen]

What sort of noise are we talking about?

 

[Elroy]

it happend in seconds, i cant say for sure

i did check the dipstick and there is still oil in the motor

it just got loud, i looked down and saw the oil pressure drop, turned off the key right away and back on, i dont know if the motor was still running, but the whole episode was over in 2 seconds and i was coasting to the shoulder

 

[Christian Steffen]

Doesn't sound good unfortunately. Strange loud noises and a drop in OP don't usually lead to a happy ending.

Hoping I'm wrong though.

 

[Elroy]

the shop called this morning, they say no spark at plug but does have spark at coil, suspect burnt rotor, did not look at oil leak yet, hopefully they are unrelated

 

[Elroy]

they say the distributor is not spinning, will pull it out possibly gear is stripped? is this common, ive heard of that

 

[DerekTheGreat]

Hmm, that could be the noise you heard for a couple seconds. I saw that on roadkill once, luckily it did not chew the gear on the cam so they dropped a new dizzy in and away they went.