My son just bought a 97 Tacoma 4x4 regular cab with a 2.7L engine for $750. We knew it had an engine issue when he looked at it, but for the price and near perfect condition of the body, it was hard to pass up. Truck shows 260k miles on it. Previous owner claimed he knew nothing about engines and I believe it. He said a few months ago, it would shut off after running about 5 minutes and wouldn't start back until 30 mins to an hour later. He then said it got worse and would start, but die after a few seconds. I started researching and found a maf sensor could cause this and we were hoping for the best. He said he just spent over $500 for new A/C compressor, refrigerant, and labor. Also said he just put a new battery in it a few months ago, but it was dead from where it had been sitting for a while.
Needless to say, brought the truck home, charged battery, cleaned maf and cranked it over but it wouldn't start. Tried shooting some carb cleaner in throttle intake and it appeared to hit a couple times, but wouldn't start. Ended up pulling plugs, checking them, regapping, did compression and spark check. Compression was low at 85-120 and plugs he claimed to have just replaced appeared to have 30,000+ miles on them. This didn't surprise me as his "new" battery was made in 2010. After re-installing the plugs, decided to check radiator and found it was dry but had leak stop residue all over it. Makes me wonder now if it was stalling after 5 mins due to overheating if it didn't have coolant.
Filled radiator up with water and decided to crank it again. Engine fired up but had a loud knock to it. Shut it off and added a little more oil then started it again. Still had knock so we decided to let it idle for a little while. After idling for about 45 minutes and checking coolant temp, knock was still there and had not subsided at all. While it was idling, we tried to locate source of knock but were unable. It sounds like it is coming from the center of the engine and speeds up with engine rpm. I had a similar knock from a bad lifter in a Dakota, but it didn't start making the noise until it had ran for 15 or more minutes. The Tacoma is doing it from start until it is turned off with absolutely no change in volume during this time. You can hear it from over 50' away. We decided to drive it around on the farm for a minute, but still didn't change.
After reading a little more, I am wondering about a valve being the problem. With 260,000 miles on it, makes me wonder if they have ever been checked/adjusted. The engine was covered with dirt/grease just like you would expect for something with this kinda mileage so checking for leaks is about out of the question. I just feel, considering a dry radiator and evidence of leak stop, it had to be leaking somewhere or it wouldn't be in there.
We discussed checking the valves, but am now debating on just pulling the engine and rebuilding it instead. I told him that if there is a problem with a valve, the head would have to be pulled and if I was going to dig that far in it considering the time involved and current mileage, it would be better to just rebuild. We both have experience with rebuilding engines so that isn't a problem.
What would you do if it was your own? BTW, I posted a couple pics so you could see it.