Intake Gasket Replacement - Advice, anything else?

[DerekTheGreat]

I know for sure the engine has very poor compression, its almost 300kms in and knocks like a mother. No coolant in oil. Thanks for the tip though. I am trying to do quick/cheap fixes to keep this ol girl going... eventually this old engine will be pulled and a new crate engine will go in! Can't believe the truck still runs, its amazing given the life its had. Cheers

Eh, it isn't worth it. When I got my truck it had roughly the same amount of 'grams' on it haha. (225k miles). Engine had a burnt valve (didn't know that when I bought it, one must always remember to do the napkin over the tailpipe trick while engine running). I thought about running that engine but somehow bit the bullet and got a junkyard 350 swapped in. Much happier. This engine uses maybe a quart of oil per 5000 miles whereas the other would could use as much a quart per 350 miles. Not to mention it runs on all eight. Take the money you'd put trying to build crutches for that one and invest towards a junkyard swap. Labor+parts for my overhaul was ~$2,300. Fresh gaskets everywhere too so no leaks. Well worth it IMO.

 

[94FSblazer]

Since you'll have the intake off already I'd go ahead and replace that stupid heater hose fitting on the rear of the intake if you haven't done that yet. Get rid of the quick disconnect crap and put a brass barbed nipple there so it doesnt corrode fail and break like the pot metal stock piece does, at the worst time...lol.

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^ This for sure! Always happens especially on high mileage engines. This was definitely the worst part of replacing my gasket. Luckily I kept it connected when I removed my intake, so when mine snapped and I had to fish out piece by piece, I wasn't dealing with the metal falling into my block. Get the brass barbed fitting instead of the auto store replacement for the quick disconnect. Good luck!

 

[92GMCK2500]

Eh, it isn't worth it. When I got my truck it had roughly the same amount of 'grams' on it haha. (225k miles). Engine had a burnt valve (didn't know that when I bought it, one must always remember to do the napkin over the tailpipe trick while engine running). I thought about running that engine but somehow bit the bullet and got a junkyard 350 swapped in. Much happier. This engine uses maybe a quart of oil per 5000 miles whereas the other would could use as much a quart per 350 miles. Not to mention it runs on all eight. Take the money you'd put trying to build crutches for that one and invest towards a junkyard swap. Labor+parts for my overhaul was ~$2,300. Fresh gaskets everywhere too so no leaks. Well worth it IMO.

Cheers Derek. Something to consider for sure. I'm starting to look into L31 crates for roughly $2K. Although, this is a ways off. Too many other things going on hah

 

[92GMCK2500]

^ This for sure! Always happens especially on high mileage engines. This was definitely the worst part of replacing my gasket. Luckily I kept it connected when I removed my intake, so when mine snapped and I had to fish out piece by piece, I wasn't dealing with the metal falling into my block. Get the brass barbed fitting instead of the auto store replacement for the quick disconnect. Good luck!

Cheers!

 

[92GMCK2500]

Update; got the idle some what fixed. Sneaky vacuum leaks were the culprit. Fixed those and cleared codes. Seems to warming up nicely at 1300-1400RPM for a few mins then dropping to approx. 600RPM in park and 450RPM in drive. I need to get a code reader to better diagnose this thing. Next mission, intake gasket. Most of the parts arrived this week! I'll let you know how it pans out.

 

[BlkBty]

Update; got the idle some what fixed. Sneaky vacuum leaks were the culprit. Fixed those and cleared codes. Seems to warming up nicely at 1300-1400RPM for a few mins then dropping to approx. 600RPM in park and 450RPM in drive. I need to get a code reader to better diagnose this thing. Next mission, intake gasket. Most of the parts arrived this week! I'll let you know how it pans out.

Was the leak the intake gasket? I'm chasing some now and have ruled out vacuum lines and TBI on top but thinking intake gasket.

 

[92GMCK2500]

Was the leak the intake gasket? I'm chasing some now and have ruled out vacuum lines and TBI on top but thinking intake gasket.

Have you checked your EGR valve / solenoid? I used a piece of hose (about 3 feet long), ran the engine and carefully listened for a high-pitched hizzing sound around the various seams/connections. Might be worth a shot?

My vacuum leak was found at the PCV hose-valve connection. A ratchet clamp fixed that. Seems to idle much more healthy now. Need scan tool to properly check but going off the tach, its visually within spec.

I've been too busy to get to the intake gasket replacement... Hopefully get 'er done in the next few weeks. Its definitely leaking coolant at the rear intake gasket seam, visually confirmed. As a band-aid, I added some Rislone Head Gasket Fix so that I could still use the truck & camper last weekend. Funnily enough, it hardly leaked a drop of coolant. Permanent fix to come.... Good luck!

 

[92GMCK2500]

Finally got stuck into this. Half way through, intake is out, cleaning has begun. 20 odd years of grime.

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How clean does the gasket surfaces need to be? I've cleaned it for a hour w' Lacquer thinner but can't seem to get it totally clean. Seems parts of the old gasket are corroded to the intake. Any tips?

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Looking good on top. About 2 hours on the wire wheel.

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