4.0 OHV fresh rebuild using lots of oil!!

[zwsmith81]

It looks like the ring on #5 had the ends of the ring at the hole in the side (per pic) and it likely wore down from lack of support on the ends of the ring and eventually slipped down the side of the piston. I’ll definitely make sure I keep mine away from said hole when I reinstall mine!

I had the rings spaced out away from the holes during install. I think it got rotated before the picture was taken.

 

[BigAssTim]

I was the engine installer so it’s all on me. I’m a perfectionist when it comes to vehicles so this hurts pretty bad. I did all the homework, spent the extra money replacing everything, taking extra time to install and still screwed it up. It’s been about 15-20 years since I put together an engine so I definitely lost some confidence. The rings were all at max gap or a little over (.22-.26 gap) so I was a nervous wreck about that. I’ve been reassured over and over by multiple machine shops that that won’t cause any problems. That bottom oil scraper ring must’ve ever so slightly slipped out of my compression clamp during install. So I am still nervous about the oil consumption. I took my time installing and torquing the lower intake manifold but when I took it back apart the bolts seemed awfully loose. I didn’t notice any contamination in the oil, but it was burning it pretty bad to go through 3-4 quarts in 600 miles. The valve seals were already installed in the new heads so I’m trusting they’re good but am tempted to change them out anyway. I don’t want to tear this thing down again!

I'm in the same boat, perfectionist and all! I'll be my installer, using all new parts as well. I haven't touched something like this in 30 years. I can definitely relate.

If I recall correctly, the lower intake manifold doesn't have a high torque value on the bolts, and I read somewhere that this is a known problem with our series of engine. From the factory, these bolts would work themselves loose and allow air to pass into the intake, fouling the plugs. It was recommended that we put Loctite on the bolts (probably 243 or something similar with high heat capability). If I can find the article, I'll post it here.

The valve seals are cheap and easy to change - just time consuming if you don't have a pneumatic compression tool. If it gives you peace of mind, I'd do it! Like you said, you don't want to do this again and what's 20 or so bucks for a little more piece of mind?

Let us know what happens!


-BAT

 

[Shran]

The lower intake bolts have a 4 step torque sequence and you end at only 12ft/lbs. You are supposed to go and recheck them after a couple heat cycles and I would 100% agree with that as I have found them loose before but after that they are generally good forever. I would hesitate to use Loctite on them as you won't be able to check them later without breaking the thread locker.

Tell us about the heads... are these new, reman 3rd party, your old ones gone through by a machine shop, or ??? Curious if maybe the valve guides are worn or weren't replaced maybe?

 

[SenorNoob]

Since you asked about the intake gasket, there is a revised gasket in 94 or 95. I only found it in the aftermarket when looking at a 95 model. It's a metal carrier with silicone overmolding. Also early manuals called for the heads and intake to be tightened together when both have been removed. Later manuals don't mention that step. Make of that what you will.

 

[gaz]

@zwsmith81
As our man @Shran mentioned, especially since its apart, have the valve guides, valves and valve seats thoroughly inspected. That is the only way that engine is drinking that much!!

 

[zwsmith81]

The lower intake bolts have a 4 step torque sequence and you end at only 12ft/lbs. You are supposed to go and recheck them after a couple heat cycles and I would 100% agree with that as I have found them loose before but after that they are generally good forever. I would hesitate to use Loctite on them as you won't be able to check them later without breaking the thread locker.

Tell us about the heads... are these new, reman 3rd party, your old ones gone through by a machine shop, or ??? Curious if maybe the valve guides are worn or weren't replaced maybe?

The heads were advertised as new with new valves/guides/springs/seals installed. I bought them on eBay from Clearwater cylinder head. I installed the 988 valve springs from comp cam.