I picked up a 90 4runner 4x4, auto, (cheap). 107,000. Runs rough and smokes a bit.

Ran a compression test, and found the left bank low. 2, 4, 6 read 0, 60, 90. 1,3,5 read 165. All plugs look good except #2 which was badly fouled. Carbonized, looks like.

Weird, huh?

Am I kidding myself to pull the left head and hope for the best? Or am I likely to be facing a complete tear down?

 

I regret to inform you that a full rebuild is in order.
Why? First reason, the crank. Don't know how long it's been like this but, the crank bearings probably suffer uneven wear. Here's a tricky idea. Call your local Toyota dealer and provide your VIN. Ask if the vechile has had its head gasket replaced. If not, you could be a winner of a new or rebuilt engine courtesy of Toyota.

 

Now you need to do a cylinder leak down test to figure out why you have such low compression. Once that is done you will know what corrective action is needed.

Gadget

www.GadgetOnline.com

 

I've got no idea how long it has been like this. I guess this idea has some merit.

Unfortunately, the gasket party has already been done. First straw I grasped at.

 

Don't have the gear to do a leak down test.

What can it tell me that pulling the head will not? I've got to pull it anyway, no?

I admit, that I would much rather pull one, or both heads that pull the whole thing..

 

You may not need to pull the head.

You may find that you just need a simple valve adjustment.

If you pull the head you will still have no idea of the condition of the piston rings.

Gadget

www.GadgetOnline.com

 

While I'm sure that's true as a general rule, with one cylinder at 0 (zero) in the compression test, a leak down is gonna tell me nothing about the rings. At least in that hole.

I suppose, tho, there are some things it can tell me. Like air rushing into the crankcase, might hint at a hole in the piston, and air noise in the intake or exhaust manifolds might be a hint about the valves.

But, really, I have a hard time believing this problem is due to valve adjustment. Unless they have been adjusted by the pistons.

Well, off to price parts and tools.

BTW, any comments here about after market rebuild kits?

 

OK I guess you need a complete rebuild, because there is no way that a valve could be out of adjustment enough to prevent it from closing. That just can not ever happen, right?

It is always good to skip sound diagnostic work and go straight to a complete overhaul.

Sorry you did not find my input helpful.

Gadget

www.GadgetOnline.com

 

Affermation is always nice.

 

Not trying to argue with you. And certainly don't mean to offend people who are offering help.

I'm just trying to understand. I don't assume I know everything, so I ask, based on what I know. Sorry that offended you.

Re - the valve thing, this engine uses shims for valve adjustment, right? I just can't "visualize", in my mind, how that setup could get so far out as to not close. Sure, could have been set so tight that a valve burned.

Jam nut type, well that's a another matter.

Thanks for your advice, hope there is more coming.

 

Affermation?

Sorry, don't get what you mean.

 

Joea if there is no compression on a cylinder and the others are greater than 25% or more than there is a bigger problem.

Sometimes working out the small problems would fix a problem but, not in this case.

The affirmation is about confirming what type of corrective action is necessary to get you back on the road.

No one here is arguing with you. Quite the opposite. Taking an assertive stance to get a brother back on the road.

Trouble shooting steps:

I wrote several articles about troubleshooting styles. Let me break it down for you.

Systematic: Grab a manual and start from step 1 to n (n being the final step)

Divide and conquer: Find what works or doesn't and isolate the problem.

Intrinsic: A problem occurs during a known event and you've fixed so many times you just pull out the tools and replace the part.

Systematic is a good starter for those who have little experience or knowledge.

Divide and conquer is good if some knowledge is known but, not enough to be decisive.

Intrinsic means you fixed the same ˟˟˟˟˟ over and over you could do it in your sleep.

 

Amusement -

Thanks, I did not think anyone was arguing, just thought I had rubbed someone the wrong way and was trying to fix it.

And I appreciate the assistance.

Your trouble shooting "schemes" are well founded and the way I approach things.

When I know nothing, I use the systematic approach. In this case a synthesis of systematic and divide and conquer might be where I'm at.

 

I do think I reign as king of bad valve adjustments here and if you think that this motor can not make 0psi on valve adjustment alone you are in fact nuts, it can and has. Secondlay.. as I think has been mentioned, find out what the heck is wrong with it.. I don't know about "crack bearings" or what effect they may have on the compression.. But I would start with the valve train. Did you drop a little oil down the left head to see if the PSI came back up?? No? Little steps.. You just bought the truck, Right? My 4Runner is currantly running with 160+ on all but #5 it is at about 60psi. This head has 4k on it since it was last adjusted and the time before that it has less than 30psi I never checked the time prior to that. Now of these last 3 re-shim jobs done by a high end machine shop / race motor builder he was able to re-adjust them and have it running like a top for about 3k at a time. The problem you ask?? Prior the these three adjustments he had rebuilt the heads. My theroy at this time is that the valves do not take well to having the 3 angle grind re-cut into them again and weaken making them tulip and basicly "bend" downward. Seeing as how you just bought this truck, you have no idea what has recently been done to it.. I have toyed with selling mine after 2 years of ˟˟˟˟in around with these heads! Heck, you could of been the buyer if I just fixed it again and said the hell with it!

 

BTW.. This is also the basic theroy of the "Jeep Thing"


Lee..... Who knows the "Jeep Thing" and all the people at the part store know me by name

 

Bearing failure will result in operating the vehcile with one bank running with near zero compression and the other running with normal compression. Please take the time to read my post again.

It's not about defining what is the problem but, why use valuable resources fixing it. The risk is high and the return is low to continue to add time and money to the engine.

 

Psst.. I did read your post.. And I still have no idea what effect CRACK bearings could possiably have on a motor..

Take a closer look at your post again..

 

Firefyter-Emt and all:

Man, I've never "met" a group as pull of p*ss and vinegar as this one. Oh, sorry "assertiveness". What a hoot!

>I do think I reign as king of bad valve adjustments here

A dubious honor, to be sure, but then I've been proud of lots stupider things.

>and if you think that this motor can >not make 0psi on valve adjustment >alone you are in fact nuts,

Oh, a "goober" perhaps?

>it can and has.

I agree to disagree.

Despite what you say, later, I just have a real hard time believing "zero", PSI. Just from "bad adjustment". 30, 60? well sure. But "zero"? Sorry, I'll have to see it. I ain't from Missouri, but I have relatives near there.

>Secondlay.. as I think has been >mentioned, find out what the heck is
>wrong with it..

Exactly why I am asking for opinions, before I turn another wrench on it.

I don't know this engine, and am certainly willing to listen to those with experience. That does not mean I will accept something that goes against my own experience (such as it is) without
expressing doubt.

>I don't know about "crack bearings" or >what effect they may have on the >compression.

Well, I did have a hard time with "crack bearings" also. And frankly, can't see how having *no* load on one (from zero compression) could crack one, or cause it or others to wear oddly. But, I was already stepping on toes here.

>But I would start with the valve train.

That I will, for sure, as it is worth a shot. I can accept tha zero compression can be caused by a valve hung open. And I'm not too proud to use a little friendly persuasion (and a little lubricant, so she don't yell) to see what happens.

> Did you drop a little oil down the left >head to see if the PSI came back up??
>No?

You mean down in that little hole? The one I unscrewed that ceramic and steel thing from, that the wire was attached to it?

Well, yes, I did squirt some oil down in there. Had to use my wife's turkey baster. Did it on all the low cylinders. Made not one bit of difference in any of them.

Holiday turkey tasted funny, tho.

>Little steps..

Uh, compression test does not count as "little"?

>You just bought the truck, Right?

Right! Full points. (wait while I change the score)

>My 4Runner is currantly running with
>160+ on all but #5 it is at about 60psi.
>This head has 4k on it since it was last
>adjusted and the time before that it
>has less than 30psi I never checked
>the time prior to that. Now of these
>last 3 re-shim jobs done by a high end
>machine shop / race motor builder he
>was able to re-adjust them and have
>it running like a top for about 3k at a
>time. The problem you ask??

I do, I do ask!

>Prior the these three adjustments he >had rebuilt the heads. My theroy at
>this time is that the valves do not take
> well to having the 3 angle grind re-cut
> into them again and weaken making
>them tulip and basicly "bend"
>downward.

Well, I have to agree with you on this one (painfull as it is). Seems like a reasonable theory.

But, no valve should "tulip", as theorized, unless, maybe, it was ground down to way too thin a "lip".

What is the name of the the shop/person, that did the valve job? I'm shopping for a good rebuilder/machine shop. And this is one I'd like to avoid.

If it's one and the same shop, maybe the problem is a tight valve guide and their adjustment consists of a hammer and some Marvel Mystery oil?

Warrantly avoidance, anyone?

>Seeing as how you just bought this >truck, you have no idea what has
>recently been done to it

Kinda getting married again, eh?

> I have toyed with selling mine after 2
>years of ˟˟˟˟in around with these >heads!

Seriously, why have you waited so long to make the shop fix the problem?

Clearly, something is really wrong with the work of whomever did the valve job.

>Heck, you could of been the
>buyer if I just fixed it again and said >the hell with it!

Well, maybe. Never can tell when someone will try to do you. Even a 4WD "brother".

FYI, I bought this truck, cheap, real cheap, *knowing* it had an engine issue, (lumpy, low power) hoping for a little luck, but not expecting any. The price was so low, I did not bother driving it very far, or checking too deeply.

Thanks to everyone for all the advice, even those I think are sniffing too much carb cleaner. No, I don't mean you.

Honest.

Happy Holidaze.

("Firefyter-Emt"? Rats. My luck I'll need his meat wagon someday and he'll recognize me. Man, I gotta learn to be nicer)

 

Joea "good show".