FJ40 sounds like a diesel (1 Viewer)

Joined
May 30, 2019
Messages
26
Location
UK
Please help.

Following a complete rebuild, my FJ40 has a knocking noise coming from the bottom of the engine.

We initially found that the cam shaft thrust plate was slightly bent and thought this was the problem. We changed it, checked all we could from underneath, bolted the motor back together and fired it up. Unfortunately, the knocking remained, albeit slightly less noisy.

We have now taken the engine back out and completely stripped it down again. We can't find a single thing wrong with any of the components and there's no sign of any unusual wear.

Does anyone have any ideas about what the problem could be.

IMG_4154.jpg


IMG_4155.jpg


IMG_4156.jpg


IMG_4157.jpg


IMG_4158.jpg
 

ceylonfj40nut

Waiting for Barn Time
SILVER Star
Joined
Jan 11, 2015
Messages
3,041
Location
TX
 
Did you plastigauge all the conrod and crank bearings to see if they are within spec? Need more information on the rebuild process. Were the thrust washers added and what were the horizontal movement? Within spec? Need to know if things were all in spec and you still have the issue.
 
Joined
May 30, 2019
Messages
26
Location
UK
Apologies, i'm no mechanic, so please bear with me.

The conrod & crank bearings were replaced in the original rebuild. I've just Googled Plastigauge and it is available in the UK, so we can try that. Thanks.

Regards "rebuild process", do you mean how the motor was put together or what work was carried out on it?

The original copper camshaft thrust plate was slightly bent and the new camshaft was 3-5mm too far forward. I bought a new steel thrust plate from SOR and the mechanic fitted it. We thought this would resolve the problem, but it didn't.
 

ceylonfj40nut

Waiting for Barn Time
SILVER Star
Joined
Jan 11, 2015
Messages
3,041
Location
TX
 
Thrust washers I mention are for the crankshaft not the camshaft. When placing the crankshaft in you need to add two thrust washers and check to see what the horizontal movement is of the crankshaft using a dial indicator. This is important to check. It could be the source of your “knock” noise.
 

65swb45

Elder Statesman
Supporting Vendor
Joined
Apr 14, 2004
Messages
28,815
Location
818-953-9230
 
 
 
I would have used a stethoscope to try and narrow down the source of the noise.

I have heard several instances of timing gears that sound almost as bad as a rod knock.
 
Joined
May 30, 2019
Messages
26
Location
UK
I would have used a stethoscope to try and narrow down the source of the noise.

I have heard several instances of timing gears that sound almost as bad as a rod knock.
You're spot on. We completely stripped the engine down and everything was fine, no witness marks of anything. We rebuilt it , carefully checking each function as we went. I've just had it tuned and it runs sweetly. The knocking noise is still audible. The mechanic thinks it's the timing gear. He thinks it will get less noisy in time.

I also read that it could be the harmonic balancer. The shaft on mine was rough, so I had it polished before refitting it. I'm going to change it just in case it's the problem.
Bump, have you located the source of the sound?
We're sure it's the timing gears.
 
Last edited:
Joined
May 30, 2019
Messages
26
Location
UK
You're spot on. We completely stripped the engine down and everything was fine, no witness marks of anything. We rebuilt it , carefully checking each function as we went. I've just had it tuned and it runs sweetly. The knocking noise is still audible. The mechanic thinks it's the timing gear. He thinks it will get less noisy in time.

I also read that it could be the harmonic balancer. The shaft on mine was rough, so I had it polished before refitting it. I'm going to change it just in case it's the problem.
 

Users Who Are Viewing This Thread (Users: 0, Guests: 1)

Top Bottom