4runner Gone Mad!

October 21, 2004

Hey all,

I have a friend that owns a 4-cylinder 1991 4Runner. It's been a money pit!! I want to relay what she's told me of her problems in the hope that someone might have any suggestions...

Her vehicle constantly overheats. It's been doing this for a long time. She's had the head gasket replaced twice and the engine replaced (from a wreck - no rebuild) once. These solutions didn't solve her problem. I took it to a radiator dude and he said that it was shot (it was trashed!) and replaced it. This seemed to help the heat problem for a while, but it has happened again.

After she got her engine replaced (in about June), when I dropped her off and followed her, I noticed a lot of white smoke coming from the exhaust (even though it was 25C outside that day). I had her pull over and it seemed that the exhaust smelled like coolant. About two days later, the Check Engine light came on.

Even after her radiator was replaced (in July), the smoke still wafts out of the exhaust. It's most noticable when the vehicle has sat long enough to cool down (ie. overnight). It does seem to go away, or is much less obvious, after driving it for a while.

I pulled the EFI fuse to reset the codes and it came on just yesterday.

I'm trying to figure out what the problem is. After researching the issue on the 'net, I'm leaning towards a manufacturer defect that causes the head gasket to leak. I haven't inspected the plugs, oil and "Check Engine" code yet.

Has anybody experienced a problem like this with the same engine? Or, can suggest any diagnosis procedures?

Thanks for your help!

Dean

PS. I personally own a Jeep CJ-7 and realize that I'm in a Toyota forum, so don't hold it against me! ;-)

October 21, 2004

Hi Dean As far as I know the 4cyl motor has no known defects although I think some of the V6 3lt versions had problems.

Its obviously still leaking and I would be inclined to seek some sort reimbursement from the mechanic but I know the difficulties in these cases.

There is no other choice but to pull the head and do it properly.Its going to destroy the whole motor if she keeps driving it.

Overnight its worse because the combustion chamber has filled with coolant.

Sometimes the radiator hoses stay hard all night as the pressure inside the combustion chamber (130psi)pressurises the cooling system (10psi?).

To do an alloy cyl head properly its almost mandatory to have it machined true.This is probably your friends problem. Also needs to be hot and cold pressure tested. Any corrosion needs to be trace welded.

When Ive needed to do work like this Ive always taken it to a specialist cyl head repair shop,works out cheaper.

If you take them to a mechanic and he will either send it out to some else to do it properly or do a half assed job because he doesnt have all the equipment.

Keep us informed.

October 21, 2004

Thanks for the reply!

After the head gasket replacements over the last year or so, she decided to have the mechanic replace the engine with a wrecker in June. I don't know what kind of symptoms the previous engine was displaying as I only met her in May, but all of the work that she's had done on the vehicle has been by the same mechanic.

Right after she had the engine replaced it overheated again, so we took it to a radiator shop and had the radiator replaced. Still overheats.

She doesn't want to go back to the original mechanic and call him on the faulty engine because she doesn't understand what he is talking about. I've offered to go with her, but she's still leary about it. I think that she's been screwed over by the mechanic, repeatedly!

It sounds like I'm going to have to convince her to take it back to the mechanic and either reimburse the money spent on the engine, or have him fix it right.

I'll update this thread as events unfold...

October 26, 2004

Update:

I checked out her vehicle yesterday and discovered a couple of things:

1. The oil was dirty, but not really the consistency of a "milkshake." (What exactly does milkshakey mean, anyway?) Though, it seems odd that, since June, it was already so dark. Possibly a poorly maintained or worn engine (it was not rebuilt before the swap). I don't think that she's put more than 1000km on the engine since she got it.

Also, the oil was about halfway between low and full (dipstick). I noticed that she had fresh oil stains around the oil filter housing. I don't think that it's leaking at the filter, but right against the engine. There weren't any oil stains on the concrete, though.

2. I ran the diagnosis and it came up with code 21 - oxygen sensor fault. I had, in the past, reset the code because I had to disconnect the Battery for a stereo install. It reappeared about two weeks later. When she first got her vehicle back, after the engine swap, the mechanic mentioned something to her about the O2 sensor, but she can't remember what it was.

3. I was going to pull the plugs the check for indications of, whatever, but I didn't have the right socket. I've picked up a 13/16 socket, so that will be the first thing that I do when I check it out again.

4. I fired up the 4Runner and checked out the exhaust. It puffed out some white smoke, so I thought that I'd take a couple of sniffs to see how it smelled. After a brief black-out, I remembered smelling quite a bit of fuel and a what I believed to be coolant. The coolant smell was more obvious after just starting the vehicle, without revving the engine to stabilize the idle.

5. Lastly, I checked the coolant level in the radiator (vehicle not fully warmed up, though). It was almost at the lip and the overflow was at the minimum mark. The last time it overheated, I told her to pick up some 50/50 and top it up, though she says that all she topped up was the overflow. I doubt that she's put more than 50km on it since then.

I have some questions:

1. Could the failed O2 sensor cause overheating? Could the computer be doing wacky things to performance/tuning that might cause the problem? A new one is about $150, so I'd hate to replace it and it not fix the overheating.

2. What is the clamped rubber hose that runs into the oil filter housing? It runs from the front of the housing straight up.

3. Are there any other things that I can do to narrow this down a bit more?

I want to either fix the problem (if possible, but I'm not confident because of the compaction of the gear in the engine compartment and the amount of effort/downtime/space that might be involved - I'm used to working on a CJ-7) or determine what the problem is so that I can take her to the mechanic and discuss the diagnosis.

She doesn't want to take back to the mechanic because she knows that she got screwed (repeatedly), so the more evidence the better so that I can convince her that she has a big problem and it needs to be dealt with.

Thanks for all of your help!

Dean :beer: