My 98 V6 is at 190K. My engine has been idling funny and I got it checked out. The mechanic said the 4th cylinder is at 145psi and the engine needs to be fixed. He actually thought I would put $4k into it. LOL This included a new catalytic converter and a valve job. He said my cat is dead and I need a new O2 sensor. That seemed odd to me because I think usually it is suggested to change the o2 sensor to see if that fixes the problem before you change the cat. He also said he was going to change the water pump/timing belt while he was in there. Those are at about 75K miles on my car which seems a bit early anyways. I'm not about to put $4K in a car that may not be worth that much to begin with.

Anyways long story short. I have 1.5 yrs before my next CA smog test. My goal is to keep my 4runner for that long and then just sell it to someone out of state or as is because I'm not about to drop $2k for a smog job. What are my odds I will make it another 25K on my engine?

 

What were the readings on the other five cylinders? Did he perform a wet test as well as a leak down test?

If the leak down produces air coming out of the exhaust (exhaust valves) or intake (intake valves) , I'd get a head job done. It may just be valve guides. If not, the rings may be gone and rebuilding the lower end may not make too much $$$ sense so then I would look for a used engine.

Any CELs thrown? If not, it may be time to change kitty.

 

Agreed. What really matters is how much of a difference there is between that one and your other cylinders. Something like less than 15psi difference is normal.

 

I bet you make it till the next smog check, i have had 2 cylinders slightly low on compression ever since i got my truck and it has ran like a champ for 3 years while supercharged.

A leakdown test is a good idea to figure out where the problem is coming from.

 

How much will a leak down test run me? The other cylinders are

1-175
2-180
3-160
4-145
5-150
6-180

What were the ratings on your truck when you bought it? Have you put any work into the engine?

 

My engine is unopened but has a fair amount of bolt on upgrades like headers/supercharger ect. Never had a problem with it at all even with a little low compression on the passenger side cylinders (at least 2 of them, maybe all 3) since i got the truck 4 years ago, 3 of which supercharged.

A leakdown tester will run you about $100 or sometimes you can rent them. Just don't get a harbor freight tester, they are worthless.

 

I don't know how the numbers lay out but is one side 175, 180, 180 and the other side 145, 150, 160? Numbers like that could be from a number of things. Like the battery was more charged when you did the first side, etc.

 

Yeah I saw that too as I was writing out the numbers. Seems a little strange. I didn't do the test. The shop did the test, so i have to take them at their word.

 

Ask them if they did a wet compression test, where one squirts a little oil into the spark plug chamber, then redoes the compression test. If the compression jumps high in those three with low readings, then probably the rings are going/gone. If not much of a jump, then more than likely it is a valve issue. The leak down test can pinpoint it further (no HF tester used here please).