yotafreakshow

What the? Sure enough, as soon as I decide to sell my 1st gen, it spites me.
1985 22rec

Seems like I have a warped or burned valve with a twist. I have the common issues: Rough idle/miss goes away above about 1800 rpm, low compression #4 cyl, pouring a little oil in the cylinder barely increased pressure, from 60-80 psi. I held a NAPA reciept against the end of the tailpipe and it sucked the paper against the pipe every second or so. Sounds like a bad valve, eh?

Here's the wierd one: the crankcase is highly pressurized, as in the dipstick is being forced out of the tube a 1/2 inch or so and oil is blowing (in strong puffs) onto the underside of the hood. Also if I remove the oil filler cap, engine running, there is almost enough pressure coming out of it to blow my hat off as well as oil gurgling past the baffle.

Head gasket, timing chain, pcv, plugs, wires, dist. cap, ect. are all new.
No vacuum leaks, timing is correct, TPS adjusted, EGR, AFM seem fine. I've been through it all.
I also re-torqued the head bolts-they were fine as well. Obviously I should have had a valve job done instead of just lapping them when I put in the chain, but has anyone had the crankcase pressure issue with a valve problem. I'm having trouble understanding how cylinder pressure is getting into the case. I had the cover off and looked at the stem seal(new as well) and it is still in place.

Could a faulty head gasket allow cylinder pressure into the oil gallies near the combustion chamber? There is no oil/water mixing or smoking going on.
It will smoke bluish after starting it in the morning, but only for a few seconds.

Any ideas? Sorry it's so wordy, just wanted to be clear.

SoCal4Running

Sory to tell you this but you have lost a piston ring, had the same thing happen on my 4runner. If your lucky it wont do any damage to the cylinder walls.

yotafreakshow

That's kinda what I was thinkin'. Cant imagine it wouldn't do any damage unless it broke and stayed in the groove on the piston. Did yours trash the cylinder wall?

SoCal4Running

Mine dissapeared, no trace of it. Did not do any damage to the piston, cylinder walls, head or anything. The motor only had 30,000 on a rebuild by the previous owner.

It not uncommon to blow rings when head work is done because sometimes when cylinders go from having no-little psi to having 170 psi bad things can happen.

yotafreakshow

Must have ended up in your cat, or muffler. Guess I'm pulling the head..again. Nice thing about the SAS is that you can pull the oil pan to access the rod caps w/o dropping the diff. Thanks for the input.

SoCal4Running

Yea just getting the pan off sure did suck, I should of pulled the motor.

Plays_with_Toys

I feel your pain! I just had my truck up for sale, and then decided to keep it. My #2 cylinder is trashed. 60psi dry, and 80psi wet. All others are at 120.

Is it dangerous for the motor to drive with a bad valve or possibly missing piston ring? The reason I ask is I would like to drive the truck back to my mom's house where I have a garage to work in (mechanic here wants close to $900), but she is 80 miles away. I'd limp it at no more than 50mph... but I don't want to make the situation worse.

SoCal4Running

It all depend, every situation is different. If the valve was hanging into the cylinder then I would say do not drive it.

When I lost the piston ring on my 4runner I drove it for over 100 miles like that, I figured that whatever damage was done so might as well go to for another week driving it.

yotafreakshow

Borrow or buy a 12 mm wrench at Wally World and pop off the valve cover. See if your valves keepers are all in place so you know a valve isn't trying to migrate into the cylinder (they don't do any good in there). If that checks out, the only other damage I can think of is a broken ring scratching up the inside of the cylinder wall and piston. If that's your problem, the damage is probably done. Open up your oil fill cap w/motor running and see if you get a bunch of pressure blowing out. It will be obvious.

With any luck you just have a burned valve, which only makes it annoying to drive. My bad cylinder psi was about the same, but as you read there is alot of compression going into the crankcase.

When you open the oil cap, the engine should actually drop in rpm and stutter a bit more due to extra air being fed into the intake via the pcv tubes on top the valve cover.
If that's the case, you are most likely losing air/fuel out the exhaust, instead of into the crankcase, as is my case. I put 300 miles on it before I realized the problem was more severe than a tuning issue. I'm opening it up Sunday, I'll let you know what I find.

dajabr

What about stuck open pressure from the oil pump? Not sure because mine blew the oil out from around the filter and this was the problem. I know the dipstick came out but never ran it long for obvious reasons.

yotafreakshow

Nope, trashed rings in cyl. #4. The top one was worn to about half it's normal width, and the bottom one was broken in about 15 places, and all pieces stayed in the groove...unbelievable, there was no damage to the cylinder walls or piston. Whatever they are made of must be alot softer than the steel used in the block. The other 3 clylinders looked fine. I'll get her up and running tommorow sometime.

SoCal4Running, I see how you could "lose" a ring. Some of the pieces were only 2 or 3mm long. A broken top ring could go right out the exhaust bit by bit.

SoCal4Running

Besure to check the ring groove in the piston itself, they can "widen" over time, especially with ring pieces movin all around.

Are you going to use a Toyota brand HG? Worth the $$

yotafreakshow

I'm using a Victor Reinz (sp?) brand gasket. Napa's house brand I believe. I put a new timing chain in my '89 pu 60k miles ago using the same one and haven't had any problems.

Piston grooves seemed fine, I used a broken ring to scrape the carbon out of them and the fit was snug, but allowed movement. I'll check the clearance with a feeler guage when the new ones are in.

yotafreakshow

Success today. New rings and rod bearings installed, she runs awesome. No leaks. Just need to break her in and see what she's really got.

SoCal4Running

Sweet, glad to here. I am still cleaning the oil off the underside of my hood. lol

4Hummer

Sorry I find this funny.

Glad everything worked out for you

Plays_with_Toys

Hey guys, just curious if the valve is moving into the cylinder, how would that look exactly. Will something be disconnected, will the spring be loose no matter what, etc? I am going to take it apart this weekend, and if viable drive it down the following weekend.

yotafreakshow

If the spring were completely loose, I imagine the valve would already have been sucked into the cylinder. You would have heard that pretty obviously, though thank god I haven't ever heard that!
Just make sure there are 2 valve keepers in each of the valve spring retainers. The keepers are like little wedges that fit into a groove around the top of the valve stems, inside the retainers. The top of the keepers should be about flush with the top of the spring retainer. Just make sure the retainer area on top of all 8 valves look the same and you should be fine, of course the rocker arms will be pushing some of them down.

adambeskow

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