Can anyone help distinguish this engine knock noise

Hello all my name is: mott
I have a: (GTO, 3000GT, STEALTH / SL, MR, VR4, TT)
It has the following issue: (be sure to describe it as best as you can. Remember to also tell us what you have tried so far)

hey everyone I have a 1993 3000gt jus put another motor in it that was stated that it had 76k miles my mechanic said everything went good when installing it but I am hearing an engine knock noise jus would like to know if anyone can distinguish the sound it is making I will attach a video link for reference thx also the guy I purchased it from said to check to see if the oil pan is hitting the crank I’m guessing this would be caused by lifting the motor back into place during installation

First thing I’d do is a visual on the oil pan but your mechanic should have picked up on this. Second check the oil level. Sounds more top end to me. Difficult from a video. Run the engine as little as possible.

yea I’ll ask him to drop the pan, it doesn’t sound like a rod knock to me

Is the sump dented? That does not sound healthy, spun bearing?

what’s the sump is that the oil pan ?

I have heard this noise before. It was caused by a slipped belt and the valves were hitting the piston.
Not saying that this is your problem but if the easy stuff looks ok, check the timing. I would not attempt to run the engine again until you find the cause.
Crank hitting the pan is more a scraping noise than a loud knock in my experience.
Didn’t your mechanic notice this noise and investigate?

that’s what I was thinking I’m gonna ask him to check it out he said it’s a bottom end knock but I’m guessing he jus judged it by where the sound was coming from

u mean slipped timing belt?

I will ask him to check that because he did tell me he changed the timing kit included everything in it and the water pump

If a timing kit was fitted then definitely get it checked but do not drive the car to him or the damage could be terminal.

yes he definitely changed the timing kit out he told me he let the car run for 20 mins to see if the noise would go away the motor was used from first class engine and they stated that it had no knocking noise before I received the engine at this point I don’t know who could be at fault but I’m gonna ask him about the timing kit and go from there

This seems a strange mechanic to me. Would anyone here consider running an engine for 20 minutes with that noise?
I hope that it is not a slipped or wrongly set belt because there is a good chance that the valves are damaged.
Another belt related problem that I have seen a number of times is where the “mechanic” pulls the pin out of the tensioner before the tension on the belt is correct. This causes the tensioner to fully open. It then has to be fully compressed again in order to get the pin back in. They tend to do this in a vice which is possible if done correctly but most people just try to wind it in as fast as possible and this causes the seal to burst. Once the seal has gone, you can’t keep the belt under tension whilst running the engine. If the belt is too slack, the timing will always be one or two teeth out when the engine is running and this will cause valves to hit the top of the piston and create the dreaded knock.
Surprise, surprise. Every mechanic blames it on a faulty tensioner but the vice marks in the tensioner piston tends to give them away.


I thought it was weird also I would think him hearing that noise would make him cut it off sooner and recheck everything I really hope I don’t have other internal damage because of it

1 Like

If that noise only came after timing belt service he should never have ran the car for 1 minute never mind 20. Check the timing immediately.

not sure it was a motor that I bought used from first class engine I think it was changed with the motor still out the car, the sound doesn’t sound like a rod knock?

Another thing is if he used a junk aftermarket tensioner. Had that happen to me once on a car I was asked to do a timing belt on.

The craziest thing was the tensioner blew when I was verifying the timing by hand. I starting turning the engine and I heard tink, so I stopped immediately and I watch the next cam gear snap over to “resting” position. I pulled the tensioner back out and I could depress it with my thumb.

We ran to several local stores trying to get another and had no luck. The owner made the decision to reuse his old tensioner, because he needed his car. I unwillingly used it, and got the car back together and it was great after that.

He called me the next day and said the car hadn’t run that good since he got it, so it ended up being successful.

not sure what kind it was but was around 200 dollars

If you paid $200 for an OEM, or especially a non-OEM tensioner you got robbed. They are like $125 straight from Mitsubishi.

for the full kit water pump and everything?

My money is on incorrect fitting.

1 Like