What should I do next with my 3.4L engine?

Torch= torque. But rest still doesn't make sense

 

Checked my valves today.
Since I already had the gasket and had it torn down this far, I might as well check the valve clearance. I was surprised what I measured because this engine had no valve ticking. I thought I would pass it on.


Valve Clearance Intake .006 - .009 Nominal .007 Exhaust .011 - .014 Nominal .012

IN (Front > Back) EX (Front > Back)

1 .007 .008 ------ .015 .014

2 .009 .009 ------ .013 .015

3 .008 .008 ------ .015 .013

4 .008 .008 ------ .014 .015

5 .008 .007 ------ .017 .014

6 .009 .009 ------ .014 .015

So to bring all the valves that are out of tolerance and the ones on the edge I need 14 shims. I'll check the dealer tomorrow...hope there no too expensive.



Glad it's nice and clean. PO must have been good about oil changes.

 

[/quote]Another question about spark plugs is I understand that Toyota went with these duel electrode spark plugs because this engine design has a wasted spark (the plugs spark every stoke instead of just at the power stroke). So the duel plugs would give longer life. But now with the long life of iridium plugs could they be used? Has anyone had good experience with iridium plugs?[/QUOTE]

I decided to go with Iridium plugs based on this video...makes sense to me.
https://www.youtube.com/watch?v=53yfHLdn41k

 

Just keep an eye on your tail pipe on start up or when idling, the head gasket is compromised if there
is residue between the block and the head and it's a matter of time before the gasket will fail completely, A leak is a leak could last 1000 miles or 100.000 miles. Your first sign will be white smoke coming out of the pipe on start up to begin with, then it's time
for new gaskets and hopefully the heads are ok. My 3.4 did this at 425,000 miles and then at 480,000 gave out( at 480,000 was blowing white smoke all the time), never had antifreeze in the oil, ended up with
2 cracked heads with the leaking gasket and white smoke on start up only and was loosing just a little antifreeze each month. Each engine will be different with this issue,
One of the big issues with head gaskets also is that the antifreeze is not changed by some owners on a regular basis.
Facts are the motor is cast Iron with aluminum heads and rust devolopes on the cast iron parts( normal) and this rust is carried through the coolant system but if not changed the rust(metal partials) are like sand paper and wears the inside of the heads because the aluminum is soft compared to cast-iron. So a lot of time you will see the heads on these motors shot because the water jacket areas are worn down and no metal left were the heads meet the block and the gasket can't hold back the pressure.
So replaced the 3.4 with
a low mileage motor with 100,000 miles. Runs great again.

 

Wow, 425K miles...I have nothing to worry about. I just sold a 89 Toyota Xtracab 4wd that I had for 12 years and only put 30K miles on it.

 

I wouldn't touch the valves. They actually tend to get tighter.

My eyes ain't so great though, do you see a worn shim? Are they gouged looking?

 

All the shims look pretty good. Even the cam lobes look fine and the bearing surface still show a machined surface finish.
I my case most of the valves were on the edge of loose and a few were too loose.
IMHO valve clearance is important. When the clearance is tight, the oil film can be squeezed out or the valve is held open a little. When clearance is loose, the valve will miss the progressive acceleration and de-acceleration area of the cam. This causes the valve to be slapped open and then the valve closes and slams into the valve seat.
I figure the stresses of loose valve is were maybe cracked heads come from.

 

Certainly truth to your theory, I won't dispute that. But your borderline to loose, not flopping around. And our ramps/rpm range just isn't radical enough to worry about float. I imagine they were loose from the factory. My truck is comparable @ 200K miles and not as clean.

They proverb of OHC, shim over/under bucket is "A loose valve is a happy valve".
If they're not ticking excessively even warmed up....I wouldn't touch them.

side note: from what I've seen of cracks in seat areas, it's from a tight valve....seat gets pounded up, valve stays open, gets hotter, pounds up more etc...craaccck. Never seen a mushroomed tip cause a crack.

 

30k miles on an '89 4x4??

I bet the guy that bought it was one very happy camper, what did you let it go for?

 

HE put on 30K, it might have had 430K.

 

Ah okay, read that wrong lol. Was going to say, damn....

 

I'd worry about fixing it myself, but that's just me, every little imperfection bothers me to high heaven until it's resolved! Lol

 

This is one of those things I would just monitor cautiously. Doesn't warrant spending the money until it causes drivability issues. If the compression is good, the oil is still separate from coolant, and the engine runs smooth what's there to worry about? I would however point out that keeping the valve train looser on these engines is a good idea as this shim over bucket design has a tendency to tighten up of the course of use and then burn valves as the valve seat becomes worn. So keep it in spec for sure but maybe toward the looser side of that spec. My exhaust valves cracked my head.... that $2500 that I'll never see again, but live and learn I suppose. The previous owner never did any maintenance to my truck so I guess if that's the only major issue I'm still happy with my little green dumpster.

 

Oops, let me clarify. I bought the 89 with 156K and sold it with 186K miles. Got a good price of $6500.

OMG...me too. I loose sleep I'm so anal about this stuff.

 

The truck is so clean I guess I can't blame you. I think your fine just monitoring but that's easy for me to say from way over here.
Depends on how much you plan to drive this one. More than the '89? or less?

 

This truck is not my daily driver...it is mainly a off road RV. I do intend to do the Mojave Road end to end and some very remote Sierra mountain trails. Places AAA will not go. So I like go through 'new to me' 4wd's pretty thoroughly. It gives me piece of mind in the middle of no where...not that there many no where's in California.

 

Here is an update. I purchased a leak down tester and here is what I found. All the cylinder had a good leak down at 3 to 5% which is very good. Unfortunately the #5 cylinder has leak down of 26%. Strangely the compression of #5 is 180 PSI. Well above the 143 PSI minimum is the FSM.
My brother has camera scope probe and here is what we found.


The top 3 pictures show a little coolant staining on the piston top. The next 2 pictures show the cylinder wall. It looks very good still. The last picture are kind of hard to tell but it looks like there is a crack between the intake and exhaust valves. I went to a local head shop and was quotes $350 just to weld the head. Need less to say I ordered a refurb'd head for $325.

I figure the engine is worth the money because the bores look good and the oil pressure is 75 PSI at 3K RPM and 14 PSI at idle.

 

Just to wrap up this thread I finally have the truck back together and is running great for the last week.

So what clearly looked like a crack on the bore scope turned out not to exist. The head looks fine and pressure tested good.



I don't own a precision flat so I checked the heads flatness this way. I could check all the gasket surfaces and they only varied no more than .001"...no problems here.


Just a close up of the staining on the block surface were the coolant had been leaking. Here is were I wished for a precision flat. I wasn't able check flatness of the deck.


New head gasket and knock sensor cable. When I was disconnecting the old knock sensor cable, one set of wire pulled right out of the connector. That may have been a problem later.


Turns out the poor leak down percentage on #5 is piston rings. The compression check on #5 is still 180 PSI with the new head gasket witch is plenty good so I let this slide...LoL. I figure I'll check the compression on #5 every oil change to keep an eye on it.

That about it, thanks for all the suggestions.

 

I used to use a thick piece of glass to check warpness. Cut from a 50s TV screen. Man, it was flat.