Valve job - rear main leak - advice

[pelagoram]

Picked up our '91 FJ80 3 years ago and have been loving the truck. 160,000 miles, no major problems. . . yet.

For the past few months, it's been running pretty rough, so took it in to our local shop for a tuneup, but still continues to idle rough

Ran compression check and sure enough, looks like we're in for at least a valve job at some point -

#2 - 60 dry - 70 wet
#5 - 110 dry - 120 wet

We've also got a pretty good oil leak on the rear main seal.

I'm a novice wrencher at best, so doing the work myself just ain't much of an option.

So, we're looking at $1500ish for the valve job and $700ish for the rear main, which it seems starts to get us a pretty good start towards just biting the bullet and finding a rebuilt engine to drop in, or possibly even looking into picking up a new (used) truck at some point and parting this one out.

My question to you guys is - based on the current state of affairs, (and assuming we can get the truck to pass emissions for another year or two), would it be a mistake to keep driving it around for a year or two - mostly around town, some limited off-road use, possibly pulling our small trailer around, or will this kind of use cause more damage to what's already there and screw us more in the long run?

Other than a loss of power, what effects will we notice? Or is this just a bad idea?

Thanks for taking the time to read this diatribe - looking forward to hearing your thoughts.

P

 

[jesspross]

I know what you're talking about, I've got a '92 with a monster thirst for the gasoline (8-9MPG around town) and seamingly WAY down on the power,also low vacuum that afects the brakes and i'm wondering if it's time to rebuild my motor or go with a 5.7 Vortec Chevy motor.

I've had to "talk" the emissions guy into giving me an inspection sticker for the last 2 years and after all the money I've spent( not to mention a considerable number of busted knuckles/weekends) trying to keep my rig on the road I'm giving some serious thought to swaping engines.

Good luck on this issue.


Jess

 

[matt60/80]

I guess I'll chime in. You say that you're a novice wrencher but in all honestly you probably have what it take to work on this car yourself. The real question is do you have time to do the work yourself. Before I got my 80 the most I had ever done was an oil change. After reading up on this site I have repacked the birfs, replaced the calipers, tie rod and drag link ends, water pump, alternator, master cylinder, brake booster, lots of other misc. things and am finishing up a head gasket job that didn't even need to be done. Oh and I did the brake booster and master cylinder in the parking lot of my aparment with mostly basic tools.

I started at the same skill level you have and have slowly worked my way to doing what I've done. But this has taken a lot of time to do. If you have the time to work on your car I say do it. Admittedly dropping the tranny is a bit overwhelming but still doable. One possibility is that your rear main isn't leaking and instead it is the sump (oil pan) gasket that is leaking. Pulling the head isn't that hard just time consuming and that is most of the cost of the head job. If you decide you don't want to work on your rig I say sell it instead of parting it out. These things aren't being made anyone and someone on Mud will be more than happy to take it on (hint, hint ).

 

[pelagoram]

Thanks for the thoughts and encouragement, fellas.

Unfortunately, time is at a bit of a premium these days as well, though idea of doing this myself does hold some allure. It just may be a while until I can get at even attempting anything.

In the meantime, is it bad to continue to drive the truck in this condition? Am I flirting with disaster?

Thanks again-

P

 

[matt60/80]

I drove my FJ-60 for many thousands of miles with a bad valve. Eventually the engine was too wore to continue driving and I parked it. You probably could get away with driving for a while.

 

[TrickyT]

...
We've also got a pretty good oil leak on the rear main seal.
...

Are you sure it's the rear main seal? 3FEs are notorious for oil leaks in the rear arch of the oil pan. It could be all you need is a new oil pan gasket (Toyota brand highly recommended for this part).

There is an inspection plate on the bottom of the bell housing. If you pull that off you can see the front side of the fly wheel/flex plate. If the rear main is leaking that will have oil on it being flung out radially (i.e, oil streaks leading back to the center of the flex plate). If the flex plate is clean then look elsewhere for your oil leak.

 

[Michael Hanson]

The oil leak can always go awhile if you top off the oil and check it Daily! The valves need doing now. 2 cents Mike

 

[lacruiser]

Thanks for the thoughts and encouragement, fellas.

Unfortunately, time is at a bit of a premium these days as well, though idea of doing this myself does hold some allure. It just may be a while until I can get at even attempting anything.

In the meantime, is it bad to continue to drive the truck in this condition? Am I flirting with disaster?

Thanks again-

P

Tom's advice regarding the rear seal is excellent.

As far as driving it with a fried valve, you won't stress the engine much by doing this, that cylinder will operate at low compression is all. You will have lower power than normal and less fuel mileage, but the engine will continue to run for a long long time that way without further damage as long as it's a valve that we're talking about here, and the wet/dry test seems to indicate that is the case.

If it turns out the compression loss is from another place (rather than through a burned valve), then that's a different matter. If the piston is cracked, you could show similiar wet/dry test results, but driving the engine like that will most likely result in catastrophic failure sooner or later, as the piston will eventually break apart. You can further pin-point the likely source of compression loss with a leak-down test. However, in most cases when wet/dry results are as yours are, it's a burned exhaust valve.

Since the compression is very low on one cylinder,the engine must be running with a pretty steady miss, almost a lope. If that's the case, did you happen to notice that this lope developed over a period of time or very suddenly? Usually (but not always) a burned valve will reveal itself over a period of time rather than very suddenly.

Since the price of these trucks is in the basement right now, it's probably a prudent option to consider looking at a later model, with the newer engine.

good luck

Dana

 

[lndcruz]

get a 95-97

 

[pelagoram]

Fellas-

Thanks for the good advice -

Great thought on checking the oil pan - went ahead on that, but looks like on this one, it is indeed the rear main seal. Ugh. . .

The engine has got a pretty good lope to it - seems like it's crept in over the last few months or so. Hopefully that's a good sign.

Looks like I'll be in the market for a big piece of cardboard to park on for the time being and getting as many more miles out of the existing engine as I can.

At some point, I'll likely be back in the market for a new truck - any years in particular to look for (or look out for)?

Thanks again-

P