Chevrolet Tahoe Engine Knock And Transmission Problem

Question: I have a 1997 Chevy Tahoe that was running great. Changed oil, now engine is knocking. Any ideas. When I changed it there was alot more oil in it than should be. Don’t know how that happened.

ProTech: Too much engine oil in the crankcase can cause engine damage, but will usually muffle the noise in it until it is drained and then filled to the proper level. If the knock is really bad, you’re probably going to be looking at major engine repair.

Anything I can try first. I put in Valve Medic and was told to change it again with heavier Lucas oil and see what happens.

Heavier engine oil will again just make it quieter, but not solve the problem. If you’ve got damage already it will just get worse. You need to fix the cause of the knock noise.

The noise stops after awhile when you accelerate.

Well you are putting a load on the engine at that time which will also hide any problems by sort of tightening things up. Almost sounds like a worn piston wrist pin.

What would you think it is it’s coming from lower end of passenger side.

If it is the lower end you’re looking at either rod or crank bearing, or even a rod/pin or piston problem. Any of these would require removal of the engine and disassembly to repair correctly.

Wow, well thank you for your help I truly appreciate it.

No problem at all! Good luck with your Tahoe.

One quick question. If it’s one of the issues your thinking what am I looking at for repair cost to go to a shop?

Yes a shop or a dealership would be your best bet for a repair of that nature. Unless you can do it yourself.

What am I looking at cost wise roughly.

Tearing into the engine is never cheap. If a rebuild is in order, you’re going to be looking at $2000-$3000 minimum. You may want to get a used engine and just have a shop install it.

Transmission Won’t Shift

Question: At times the transmission in my Chevrolet Tahoe will not engage in the drive mode. I shift to 2nd gear and the vehicle will move forward and then i shift into 3rd. The oil pressure gauge reads about 65 p.s.i. when it is at 40-45 normally. Check engine light goes on and at times turns off. All codes pointed to the transmission. Transmission shop had the vehicle for 3 days and could not locate the issue. Said transmission is fine and it probably is electrical related. Any suggestions.

Answer: There is nothing electrical that would prevent the transmission from going into drive range, 1st gear. Electrical solenoids control the other gear upshifts. It is an internal problem. Most likely a sticking valve or valve body problem. You could try to do a fluid flush service along with a filter change.

This will sometimes free up a sticking valve or remove any debre that may be in there. Also add a cleaning additive before the fluid flush and get the trans hot..

The oil pressure problem is most common to be just a bad sender switch. For the check engine light, I would need to know what codes were stored in the computer before i could offer any help with that problem.