3yotas

Well we have a 1998 toyota 4runner with 3.4L engine 110,000 miles. The check engine light has been coming and going for a a couple of months, they replaced a coil.. it has multiple misfire cylinder codes and has out of the blue developed a knocking in the engine. (the knocking occurs at start-up and continues as you are driving) I took it to two mechanics, both whom do not believe it is the the timing belt (which has not been changed) the both say its something in the engine, (a rod, valve, etc. ) they would need to open it up to see what is is, the one mechanic said was not worth it, I should just scrap it and I do not really trust the other guy (he was suppose to fix it the first time, and now its worse)

I don't want to scrap the thing we have a 1997 with 199,000 on it and its still running strong. We have only had this one for 8 months and put 10k on it!

So I'm wondering should I have someone tear it apart? Is it worth it? What can I look to spend?

Thanks for your help!!

tigertowncruiser

The main problem is finding a mechanic you trust. it could be something simple or a major rebuild needed. A mechanic can tell the difference from valve or upper knock from a rod knock. If its in the top end , your costs will not be that great. It could also sound like knocking from misfiring badly. Timing needs to be checked and pinpoint the knocking. Does it run smoothly at idle when it knocks ? If it ends up being a rod knock , your cheapest option will be putting a used motor in. 110,000 is very low for this motor

zlathim

A compression test followed by a cylinder leak down test on any cylinders with noticably low compression should help pinpoint the problem. It will at least tell you if it is a valve problem or something else. Any mechanic worth his tools can do that. "Opening it up" refers to engine teardown, which should not be required for diagnosis, but it will cost some money to have the tests performed. Maybe $50-$150 depending on the shop rate in question. From what I have heard from you in this thread, I would recommend taking it to someone else.

I had a 2.7 litre Tacoma throwing the multiple cylinder misfire code. All the exhaust valves were below minimum specified clearance, and cylinder #1 had burnt exhaust valves. It was easy to diagnose and moderately challenging to repair at home. A $35 leak down tester from harbor freight worked great for the diagnosis.

If you can't do repairs like this yourself, you are really at the mercy of the mechanic. Good luck. Find a good one and stick with him.

j-man

I always opt to do the simple things first. Clean your MAF sensor with QD electronics cleaner, change your plugs, wires, coil packs, fuel/air filters, and run a can of seafoam thru your pcv valve prior to giving it a tune up. Once the simple things are taken care of, re-check everything and if its still giving you problems then take more aggressive action. Its usually something really simple cause these motors are extremely strong.

zlathim

You can do all that stuff and still not fix the problem. I prefer a thorough diagnosis to the "shotgun" approach. New plugs, wires, coil packs, seafoam, etc, etc are expensive. I'd rather find the problem and fix it and worry about all that other stuff at the regular maintenance intervals.

SchooBaka

Make sure the crankshaft bolt is not coming loose. A loose crank pulley bolt can cause a knocking as well as the random multiple misfire codes.

treeman89

I have a question regarding my recent compression test on my 1998 4 runner 2.7 litre.
Is this considered good? What is considered Factory Compression?

CYLINDER 1-210, CYLINDER 2-210, CYLINDER 3-200, CYLINDER 4-200 PSI