Toyot Limon

First off, hello YotaTech'ers. I've browsed through some of the recall posts regarding 2nd gens and all that jazz. My issue is, I bough my 94 4runner sr5 last summer and it ran fine (if you ignore how it has undergone total wussification). Recently the head gasket blew. I later found out that the recall had already been performed back in 7-98 and it blew again. I don't know what the mileage was when it blew the first time as i'm the 2nd owner, but now it is around 151k. I'm looking for opinions on how to approach the subject. I feel that if i go in and explain to the dealer that fixed it the first time they will laugh and send me out the door. The car is already at the mechanic being fixed as i cannot afford another week w/o transportation. Is there anything i should ask the mechanic to check for or replace while he has the head off? Thanks in advance.

4RocRunner92

Timing Chain?

ThomasJ

Knock sensor and wiring. (mostly the wiring)

Have the heads checked to make sure they are not warped. If they are warped and you dont fix them your new headgasket will not last very long.

Check valve lash and adjust as needed. Its really easy to do when you have the heads off.

94x4

I know, that there is more than one thread on this topic.

Try typing "head gasket" into the Search window to see what you come up with..., I'll bet that it answers all of your questions.

Toyot Limon

I know there is too 94X, but my main issue is that a 2nd gasket blew and was looking for a cause. Thanks to the rest of you, i'll make sure all that gets done as well.

94x4

Well, you've said that you've "...browsed through some of the recall posts regarding 2nd gens...", but have you gone out to the main page and typed "Head gasket" into the Search window to check out the results from the entire site???

Toyot Limon

how do you think i found what i did? Most of them are just people saying the same thing over and over and over, mostly useless whining and complaining about how they couldn't get the work done for free or how they can't believe that the gasket blew so early etc. I'm looking for a reason that the head gasket was blown a while ago, and why it could have blown again and what else i should be looking for. I'm getting answers, and i understand your concern for repetitive posts. Thanks.

94x4

Okay then, the best guess for you is that the block itself needs to be decked to insure a tight, flush fit as all of the attention seems to have been focused on the heads alone.

Bumpin' Yota

I have heard a few theories....

1. Toyota stopped useing asbestos in the HGs halfway through 91 and the HG's that replaced it were faulty. This problem evidentally continued until late 94 to early 95. (probably the case on the first HG)

2. OEM TTY bolts REused to secure the heads. (The bolts used to anchor the heads are typically torqed to 35ftlbs (iirc) and then tuned 90* + 90* again.) This stretches the bolts so they CANNOT be reused. This is the biggest issue with recall work being done - they all reuse the origional, stretched out, bolts and guess whaty? No clampy forcy and HG blowy!

3. (this one i scoff at) OEM TTY bolts arent torqued enough or consistantly enough across the head.... (They why do I have 265,000 on my OEM HG?) And the torquing procedure did not change from mid 91, when all of the HG issues popped up.

4. Exhaust crossover dumps excess heat casuing HG to blow. (I REALLY scoff at this one) Same arguement as 3... The crossover does dump a lot of heat on exhaust valve #6 causing it's stem to stretch faster than the rest but thats it...




Now for things for your mechanic to replace...

timing belt
water pump
thermostat
timing belt tensioner
timing belt idlers
belts
hoses
knock sensor
knock sensor wires
head bolts (ALL of them)
valve cover bolts (the heat soaked old ones will snap easily)
PCV valve (or do the pcv mod like I did)

have all 6 injectors flow tested and ultrasonically cleaned (well worth it for the peace of mind alone!)

check valve lash (particularly on #6 exhuast - should be done every 80k miles)
check dash pot
check tps
check vafm

since you are having the heads pulled....

have them FULLY rebuilt and have 1mm oversized exaust valves put in.
port and polish too
flow test before and after.

have the heads resurfaced and resurface the block and perhaps hone the bores...

Do not deck the block unless you want your timing to be slightly off or if you want adjustable cam gears....



Ive done most of the stuff above save the head work...*knock on wood* and the 3vze is EASY to work on! Anyone who says otherwise needs to dive into a kawasaki or suzuki's innards....

94x4

He could easily reset the timing after decking the block and enjoy the slight, yet additional, compression and horsepower/torque.

Toyot Limon

That's what i was looking for Bumpin, good stuff. Thanks!

tabb

I agree with Bumpin, decking your block and heads should be of the LAST resort!! Not only will it affect your Cam timing (not to be confused with ignition timing), but it will also increase your combustion chamber/engine temps, increase the chance/ease of pinging and if not done properly, will affect the alignment and sealing of the intake manifold.

The lastest Toyota HG design for the 3.0L utilized a teflon coating to allow the heads to slide as they expanded and contracted during normal engine warm-ups and cool downs of everyday operation. I would save the old headgaskets and possibly check part numbers to see if they were of the latest design.

If I remember correctly, Toyota tech's were only block sanding the head surfaces and decks for the HG recalls, not sending them out to be machined. If excessive warpage or pitting was occuring, short blocks were being installed ( at least under warranty anyways ).

motoracer47

:hijack thread on: ive got a question relating to this, didnt want to waste bandwith with a new thread. ive got a very late 95(i believe in the last 3 months of manufacture for the 2nd gen. anyways, ive got a ticking sound coming from the engine bay. i figured the valve lash needed to be adjusted, no biggie. ive been meaning to get to it but have not had time, ive had it for about a month now. it seems to be slowly getting louder, now im starting to wonder. it almost sounds like a exhaust manifold has a crack, which will make a tapping noise similar to a quarter being tapped on metal. has there been issue with cracked manifolds? or is this just a a valve lash thing, maybe made worse by cylinder 6? obviously without hearing it its tough to say, just wanted to see what you guys/girls think. thanks, brad