4.0 OHV blowby, next steps

[Shran]

I think I know the answer to this already but I need some more opinions. My new '94 truck came to me with a variety of issues, namely coolant loss/steaming etc that resulted in me removing the heads and having them checked... they were like new but warped so I had them resurfaced and reassembled the engine. If you want a little more of the story, here is my build thread, start at post #7 https://www.therangerstation.com/forums/index.php?threads/project-11-new-daily-driver-94-ranger.206628/post-2013027

Now that the engine is back together I have some other issues which include (1) significant pinging under load, (2) a large oil leak in the front up high somewhere and (3) quite a bit of blowby - this was present before I tore into the engine but I assumed it was steam, there was a lot of snot on the oil cap. See this video (from after my repairs) -

I have replaced the PCV valve, which did not help. The old one was probably fine. I guess I feel like the blowby issue is related to the oil leak issue, IE crankcase pressure blew the RTV seal out there.

I have not done a compression test or leakdown test yet - not sure if it's even worthwhile.

Correct me if I am mistaken here but I believe my next steps would be to pull the engine and have the bottom end gone through? I talked to a couple other people about this and they felt that either I've got a bunch of stuck rings or the previous owner drove it around a lot with coolant in the oil and washed out the cylinder walls and who knows what else. Either way it needs to come apart again to fix the oil leak at minimum but I'd hate to do all that work just to have it blow out again.

Thoughts?

 

[RobbieD]

Does it still have coolant loss after the head work?

I don't think that a compression test would be a waste of time, and I'm taking it that you got a look at the cylinder walls when the heads were off.

Assuming that when the heads were off and checked that nothing wrong was found with chamber cracks or valve seating, as long as the new gaskets sealed properly, the rings do become suspect.

A compression test would give you a better idea of engine health in general, and might possibly reveal that issue is related to one or just a few of the six cylinders.

 

[Blmpkn]

What about an air oil seperator? Might have to drain it every day lol but it might at least save the tops of your pistons. Could be a decent bandaid for the meantime

 

[Shran]

Does it still have coolant loss after the head work?

I don't think that a compression test would be a waste of time, and I'm taking it that you got a look at the cylinder walls when the heads were off.

Assuming that when the heads were off and checked that nothing wrong was found with chamber cracks or valve seating, as long as the new gaskets sealed properly, the rings do become suspect.

A compression test would give you a better idea of engine health in general, and might possibly reveal that issue is related to one or just a few of the six cylinders.

No coolant loss after. Heads checked OK after resurfacing - they appeared to be remanufactured heads that the PO installed very recently. Original coolant loss issue from what I can tell was caused by mistakes made when they installed the heads.

Cylinder walls had a lot of coolant staining in the top couple inches - see below. Otherwise there was a fair bit of crosshatch remaining and no ridge at the top... I was advised not to worry about the stains. The cylinder walls felt nice and smooth so I assumed it was just cosmetic. I will run a compression test - I guess at this point I really suspect it is a ring issue and IF that is the case, I might as well just pull it, have it honed or bored and inspect everything else. I just want to make sure there is nothing else to check before I go to that much effort.

What about an air oil seperator? Might have to drain it every day lol but it might at least save the tops of your pistons. Could be a decent bandaid for the meantime

I don't really need to drive this truck at the moment and cost is really not an issue - I guess I would rather just fix it right now, I have plenty of other vehicles to drive so there is no need to limp this one along.

My plan was to buy a Maverick later this year but this truck came along at a very reasonable price. I have about $3000 into it right now so spending another ~$1500 (guessing) on going through the short block will be money well spent... that ~$4500 total is about 12% of what I would have spent on a new truck.

 

[RobbieD]

I guess at this point I really suspect it is a ring issue and IF that is the case, I might as well just pull it, have it honed or bored and inspect everything else. I just want to make sure there is nothing else to check before I go to that much effort.

I would be going along the same line. You'll know for sure when you get eyes on the rings and measure the cylinder bore.

If it's just a re-ring and a hone on the original bores, it'd be a no-brainer to me. That's a clean truck, and the '94 is a sweet-spot year. You'll end up with a like-new truck that'll last many a mile and a long time.

Good examples of these older trucks are getting harder and harder to find. They're a good mix of common-sense technology and yet are relatively simple and easy to maintain and repair.

 

[85_Ranger4x4]

IMO drive it, get some heat in it and see if the rings come back around.

 

[Shran]

IMO drive it, get some heat in it and see if the rings come back around.

The only thing holding me back from doing that is the oil leak. I bet if I drove it a hundred miles I would lose a quart of oil out the front of the engine...it is that bad... I just would hate to make a mess like that. Everything from the water pump down is coated in oil now just from my 40 mile drive on Wednesday. And if my theory about blowby blowing out the front lower intake RTV seal is correct, and I went ahead and resealed that again, I might waste a whole night into a pointless repair... know what I mean?

If it wasn't leaking and/or I was confident it wouldn't blow out again I'd go that route.

 

[85_Ranger4x4]

The only thing holding me back from doing that is the oil leak. I bet if I drove it a hundred miles I would lose a quart of oil out the front of the engine...it is that bad... I just would hate to make a mess like that. Everything from the water pump down is coated in oil now just from my 40 mile drive on Wednesday. And if my theory about blowby blowing out the front lower intake RTV seal is correct, and I went ahead and resealed that again, I might waste a whole night into a pointless repair... know what I mean?

If it wasn't leaking and/or I was confident it wouldn't blow out again I'd go that route.

It will quit leaking eventually, I guarantee it.


Yeah, I would fix that and then see if just needs a little action. Waste a whole night on a pointless repair or rebuild an engine down that just had stuck rings?

 

[Shran]

I know, I know... there is no guarantee that I didn't mess something up when I dropped the lower intake in. I have had 100% success with those so far but maybe it is the mechanic at fault.

Maybe I could just give it a few snorts of Comet first... ? Or a lil ATF down the throat? I hear those old tricks unstick rings sometimes...........

 

[RobbieD]

but maybe it is the mechanic at fault

Yes, it's always the mechanic's fault. You just need to sell that truck to me . . .

 

[4.0blue98]

The only thing holding me back from doing that is the oil leak. I bet if I drove it a hundred miles I would lose a quart of oil out the front of the engine...it is that bad... I just would hate to make a mess like that. Everything from the water pump down is coated in oil now just from my 40 mile drive on Wednesday. And if my theory about blowby blowing out the front lower intake RTV seal is correct, and I went ahead and resealed that again, I might waste a whole night into a pointless repair... know what I mean?

If it wasn't leaking and/or I was confident it wouldn't blow out again I'd go that route.

You just need to use some chunkier oil...

 

[Roert42]

You just need to use some chunkier oil...

Just fill the crank case with gear oil. It’ll be fine.

 

[Dantheman1540]

You sure the crank case is venting properly? I had an oil leak that bad 100miles=-1qt and it was because I was dumb and mixed up crankcase hoses essentially blocking the escape of pressure. Which ended up blowing out some seals and just jetting oil out of every crevice.

 

[gaz]

@Shran ,
I would:
• verify which series heads are on your 94 engine, both of the 94's I've come to posses had been rebuilt using 98+ spec fast-burn combustion chamber heads. If you do have 98+ spec heads with 94's small dish pistons, you no longer have a stock 9:1 compression ratio engine and it may desire a strict diet of premium fuel (pinging).
• depending on how much was milled from your heads (again, this machine work will also raise the compression ratio of your engine) to take out the warped surfaces, you may need to have some machining done to your lower intake manifold to match it (valley gasket alignment).

 

[Shran]

You sure the crank case is venting properly? I had an oil leak that bad 100miles=-1qt and it was because I was dumb and mixed up crankcase hoses essentially blocking the escape of pressure. Which ended up blowing out some seals and just jetting oil out of every crevice.

Pretty sure I have it right... I don't see any hoses run differently on this one compared to my other 4.0 powered trucks.

@Shran ,
I would:
• verify which series heads are on your 94 engine, both of the 94's I've come to posses had been rebuilt using 98+ spec fast-burn combustion chamber heads. If you do have 98+ spec heads with 94's small dish pistons, you no longer have a stock 9:1 compression ratio engine and it may desire a strict diet of premium fuel (pinging).
• depending on how much was milled from your heads (again, this machine work will also raise the compression ratio of your engine) to take out the warped surfaces, you may need to have some machining done to your lower intake manifold to match it (valley gasket alignment).

I'm thinking you may be onto something with the heads. I wish I had paid more attention when I had them off, but I am pretty sure they had the small chamber heads. I gave them a cursory glance for casting numbers and only found one that was like 08 or BO or something like that. From what I remember they have a different chamber shape than the 93TM's I have on hand. My fault for not looking closer at that.

I rechecked my lower intake bolts today and found some loose ones. I followed the torque specs to a T so I'm not sure how that happens - I always re-check and they are always pretty close... but never like finger tight. Fixing that, I put another 30 miles on it and about 10 of that was with a fresh tank of premium. The pinging is maybe a little better but still unacceptable.

I ran it pretty hard, speed up from 30mph to 70 and was manually shifting at about 4500RPM. Repeated that a bunch of times. Brought it back to the house and the oil leak is just horrible. So at a minimum I need to pull the lower intake again... kind of a weird thing but if I crack the throttle with the hood open, I get a little puff off smoke for a second or two from the upper rear of the engine somewhere.

I did check the trans vacuum line, it was dry, don't think it's sucking ATF.

Thoughts?

Option #1 in my mind is changing ONLY the lower intake gasket and running it hard again for a while.
Option #2 is swapping my new 93TM heads on as I know they have not been machined down and just not using the current heads - knowing that I may have to pull it apart to go through the short block if the rings don't free up
Option #3 is pulling the engine, doing a re-ring/freshen up with the 93TM heads
Option #4 is pulling the engine, re-ring/freshen up with 98+ pistons and my current heads and maybe machining the lower intake to match

If gaz is right about the heads/compression ratio deal then I am stuck with running premium or better fuel forever. I guess I would rather not do that, the goal here is just a stock engine.