Nader

Thanks for taking the time to read this and respond. I'm not an auto expert by any means so sorry for any ignorance in my message. I tried finding some clues to my question on this site, apologies if I missed an exact post on here.

I've got a 2003 Tacoma Prerunner Doublecab that has 160k on it and dealing with some Check Engine light issues. My mechanic replaced plugs and coils and after all that has narrowed it down to low compression #2cyl, I believe it measured at 120psi. He then advised I needed a valve job for about $1200. (Its worth noting the truck had a valve job at about 110k/5 years ago. I'm guessing he did a poor job.) Also worth noting that on occasion the CE light will flash and it's my understanding this is a cyl misfire?

I took my truck to the dealer to get a second opinion and upon diagnostic the same cylinder came in low compression but their advice was a replacement of the gasket for about $1200.

The dealer did indicate that they wouldn't truly know what the problem is until they dig into the engine which would cost me a min of $900. So rather than have them go for a gasket replacement and have them potentially itemize several other things, I'm considering asking them for a quote on some other possibilities. If it is a valve job, wouldn't they replace the gasket anyway?

For example, I would expect a quote something like this:

Engine investigation: $900
If Gasket replacement: + $300
If Valve job + $XXX
If Cracked cylinder + $XXX

Are there any common potential problems I should be asking them to quote?

I'm also welcoming any other insight. Thanks in advance.

Texas_Ace

Well, I would run a leakdown test, that should give you an idea of where the problem lies to start off with.

Any overheating issues? Whats your oil and coolant look like? If those are all fine it is safe to assume that the head gaskest is ok.

Then see what the leakdown test says. Should be able to figure out if it is bottom or top end with that.

Personally i would say forget having them fix it no matter what. You can get a whole new motor for that kind of money, thats what i would do. Swapping a motor is not that hard, get a weekend with a friend and most mechanically inclined people can get it done.

My compression is a little low in 2 cylinders as well, in my case i have stuck rings as the cause, i would not be surprised if yours is the same. I just keep driving mine, stuck rings doesn't really effect how it runs, you just have the change the oil more often so i get rotella oil for $20 a jug at walmart and change it every 3k miles tops.

My plan is to drive it till it dies and then replace the motor with another one, or build it. But i can do all my own work, not an option for everyone.

If the motor already had work done inside of it though and it still has problems, not sure i would want to have more work done on it over just getting a replacement motor.

Nader

Thanks TA. Heat and oil seem to be normal. Personally I don't have the skill or equipment to get in there and swap motors. Though doesn't sound like a bad idea at all. I found a mechanic that was recommended on this forum who's opinion is that since it's had a valve job before, that the valve seats were never considered in the job thus it's likely to be the problem. I'm leaning towards taking it to him since he seems to have a good reputation here and on Yelp. Though, I'm still waiting some more feedback to make a decision.

Texas_Ace

Swapping a whole motor for another whole motor is not that hard really, just a lot of unbolting and then rebolting stuff into place. With a friend to help with the heavy lifting it is really not hard. I have pulled motors in an afternoon by myself from cars for the first time. Cars i know are even faster. If you can live without your truck for a weekend or a week is even better, then most guys can do it if you are mechanically inclined or have a friend that is.

If that is over your head, then try to figure out the problem, like i said a leakdown test should at least tell you if it is a problem in the top or bottom end.

If it is top end, then it will need to be looked at as it will just get worse, bottom end it could go for quite some time before giving you any problems if it is stuck rings like mine.

offset442

its likely a burned or cracked exhaust valve, for some reason the number 2 valve goes on a lot of V6 motors first, it will cause a miss fire at idle when it gets really bad but goes away when you get to 2500 rpm, but still leaks fuel into the cat and burns it out.....

the way i tested mine was to just install a compression tester and start the motor, I got 80 psi at 900 rpm and 210 psi at 2500 rpm, shoult have been 171 pai at 900 rpm.

when i took the head off the valve has a radial crack big enough to stick a #2 flat head screwdriver tip through, I get a rebuilt head from auto zone for $500 and a gasket kit off the net for $50 auto zone wanted $250 for the kit, also you could probably get a machine shop to rebuild your head for cheaper....

good luck i plaided hell with the exhaust bolts and nuts, once you get them off if you are that luckie never ever reuse one of them throw them away and go by brass replacements i learned this the hard way that Toyota has perfected self cross-threading nuts and installed them on every exhaust part.

good luck

Nader

Thanks, based on my research and talking to several people, it's pretty hard to determine exactly what needs to be done without breaking down the engine and digging in there. (by the way this is a 4cyl engine) I'm not really qualified to do any work so I need a mechanic to do it. I found some guys in San Diego that were recommended here, but willing to hear from any other SoCal pros.