Exhaust Valve stuck open

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DavidAW

DavidAW

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Hi All,
Hoping someone can check my troubleshooting method and confirm diagnosis. And also offer options for next steps.

85 FJ60 desmogged.
Symptom, have a loss of power over last year, lots of oily water out exhaust. Also blowby symptoms, like smoke out of oil cap, excess oil in air cleaner.

Did compression check, # 2 is at 30psi, others are OK ranging from 130-150.
Wet test on #2 did not make a change.
Suspected valve.

Pulled valve cover, verified that when valves were supposed to be closed there was no tension on the rocker/ and a gap. Valves appeared to be up and closed.

Loosened both valve adjustments to be sure both are closed.
Put 100 psi air pressure into #2 cylinder and can hear air at exhaust pipe. Not a big whoosh, just a constant hiss.
No noise at Carb and no bubbles in radiator.

1st question is if this definitely a leaking exhaust valve, or could it be another cause?

2nd, is it possible to possible to remedy w/o pulling the head? Like seafoam treatment etc.

Thanks for any relies.

Dave
 
Head needs to come off. But don't fret. They all eventually have to come off for a freshen up sooner or later. Exhaust valves are wear items on a 2F.
 
Thanks
Does it sound like I have the right diagnosis as the exhaust valve. Trying to eliminate the big stuff I cant do, like rings.

Is removing the head as straight forward as pulling off the manifolds, etc. and lifting it out?
Once off, can I just clean up/re-surface the valves and re-assemble?
I'll certainly research it more before an attempt but trying to get a level of effort.
 
Just to be clear, the valve is not stuck open. The exh valve is starting to burn away on the face. If it was really sliced up (or stuck open) the gage would read zero.
 
FJ40Jim said:
Just to be clear, the valve is not stuck open. The exh valve is starting to burn away on the face. If it was really sliced up (or stuck open) the gage would read zero.
Click to expand...

Hey Jim, makes sense. I was picturing some crud keeping it from fully closing. But I have no exp that far in the engine.

Would you say that from what I tested that it is a Valve issue?
If so, is removing the head and fixing the 1 valve something I could do myself for the cost of a gasket kit and some now bolts?
Ive had the carb and manifolds off before, it looks like just 1 step further.

Thanks
Dave
 
Yes you can do most of the work yourself, but I'd let a machine shop make sure the head is not warped (probably deck it a bit) and go through the valves.
 
Yeah, if you've taken off the manifold and carb before, you can DEFINITELY take off the head. The FSM has a good drawing of the order of disassembly.
Just label the crap out of everything and you'll be fine. Don't rush.

If you've got room in front of the truck, I highly recommend using an engine hoist to lift (and replace) the 82 lb head. Although it can be muscled off by hand, doing so is hazardous for your back. And it's very tricky to place it carefully back on the new head gasket when installing, using the heave-ho gorilla method.
 
What they said above.

It's not extremely technical work and requires no special tools, so should be do-able for a conscientious shadetree mechanic.
 
You'll be fine. I've done 5 heads. 3 fj40, 1 MB 190E, and a 1957 Allis Chalmers tractor. And honestly there is a lot of shade under my tree as far a mech skills go. That Allis Chalmers head made the 2f seem lightweight.
 
Thanks
Assuming it is a bad exhaust valve, does anyone know what I should expect to pay a shop to fix.
I have a local head shop that charged me $100 to resurface the manifolds last year.
 
Couple hundred bucks to wash, mag, mill, valve job.
if they have to replace the expensive Toyota valves or springs, consider upgrading to less expensive SBC valves &hardware.
 
I had a head done at a machine shop for my 62 last year. I bought all new exhaust valves (they were past re-cutting) and valve seals and dropped them off with the head. It was $250 to inspect, clean, mill, cut the seats, cut the intake valves, and reassemble the whole works. The springs, keepers, guides and intake valves were all in spec and were reused.

By the way my truck had a chunk of one exhaust valve break off which led to this job. (Truck came to me this way.) The chunk was later found trying to escape from the muffler, some time after the repairs.

Some details and pics of the carnage are here:

I've heard 3FE's can get filthy inside...

image.webp


image.webp


image.webp
 
Last edited:
Hi All,
I sacked up and pulled the head today.
Was pretty straight forward just time consuming.

Here's what the valves looked like after pulling it

valves-1.JPG



I have the head on the bench and put water in the #2 Exhaust for 40min or so. No leak.
Dumped the water and filled with Gas. It started leaking in a few min.
So I fell better that at least the #2 exhaust valve does seem to be the issue

leak.JPG

Gas seeping at #2 Exhaust

Here are some pics of the #2 cylinder.
If anyone sees any issue please let me know. I'm hoping rings are OK and the 30psi compression is this valve.

cyl2-c.JPG


cyl2-b.JPG


cyl2-a.JPG


Thanks for everyone's help
 
Well turns out my diag was not 100%.
After a cleanup on the block and pistons it was obvious that #2 had had some trauma.
Not a hole or anything but something made the passage at some point in the last 31 years.

#2, something shewed up the manifold side.
20160529_171403.jpg


To check the ring seal,I put some oil in the cylinder and hit it with a toilet plunger that had happened to have a small suction cup.
#2 leaked past the rings when pressed hard. #1, by comparison was tight.

Video: If you turn up you speakers you can hear it pissing oil in the the pan below.


So now I'm researching the options of fixing one piston/rings w/o removing the engine.
Looks possible...
 
For those reading this later, be careful appling so much air pressure to a motor installed in a manual trans vehicle. If it's in gear with wheels on the ground, 100 psi down the cylinder CAN make the vehicle move.
 
Wile E Coyote said:
For those reading this later, be careful appling so much air pressure to a motor installed in a manual trans vehicle. If it's in gear with wheels on the ground, 100 psi down the cylinder CAN make the vehicle move.
Click to expand...

Yeah that brings up a point. The Original Post was meant as a request to find out if I had really diagnosed the problem before tearing into the engine.
Obviously I was not correct. Hearing air escape at the exhaust was not the full issue. I did not hear the greater air volume hitting the lower engine past the rings.
So if you are still reading this, take any of my troubleshooting techniques with a grain of salt.

Wile, I hope 100psi will move the vehicle cause that's about all I have on this engine. :)
I usually have the other issue, trying to had turn the engine with it in gear. I usually figure it out after a bit.
 
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