Bad noise coming from engine

Reply Subscribe

Thread Tools

Search this Thread

Oct 13, 2002 | 12:18 AM

inliner

Thread Starter

Senior User

Joined: Jul 2001

Posts: 423

Likes: 0

Bad noise coming from engine

Was gettin off the freeway ramp yesterday when I heard a clacking noise accompanied by a loss of power for about two seconds then it went away. Today I took off the valve cover to see if one of the rockers had loosened up, but they were alright. I started it up and it was running rough so I checked the vacuum and it was only 10inches, normall it's 15 so I checked my timing and it was off by 4degrees, so I put it back to 10degrees and it smoothed out again with 15 inches of vacuum. But when I hold the rpm's at about 2500 the engine will be smooth and then loose power, stumble and then smooth out again with that clanking noise happening just after the stumble. I pulled the plugs and they are all clean except for the #2 that has a little carbon but is not wet, ran the motor with valve cover off to check valve action and notice a lot of blue vapor coming from some of the pushrod holes. I thought I might have broken a ring or maybe holed a piston but then wouldn't that cause the vacuum to fluctuate. I'm going to try and run a compression check tomorrow. Any other ideas as to what the problem might be?

Oct 13, 2002 | 09:37 PM

taz3fan

Junior User

Joined: Sep 2002

Posts: 55

Likes: 0

Bad noise coming from engine

i would say check timing chain probly stretched and jumped time needs to be replaced and check push rods and valves......hope this helps

Oct 14, 2002 | 02:31 AM

inliner

Thread Starter

Senior User

Joined: Jul 2001

Posts: 423

Likes: 0

Bad noise coming from engine

I checked valve action while the motor was running and everything looked OK and these motors are gear driven so no slipped chain. Whats weird is that the problem is intermittent and not constant.

Oct 14, 2002 | 10:02 AM

badboyina67

Senior User

Joined: Dec 2001

Posts: 396

Likes: 0

From: Ohio

Bad noise coming from engine

Just rebuilt my 240 and let me tell ya...it made a HUGE difference. As for your problem, it is the timing gear. The one that drives the camshaft is a fiber-type material, designed to break so no further damage will be caused. Having said that, I would be willing to bet there is a crack on it somewhere, or you may have sheared a tooth or 2 off of it.

It's time to crack that timing cover off, and find the problem.

Ken

Oct 15, 2002 | 05:16 AM

inliner

Thread Starter

Senior User

Joined: Jul 2001

Posts: 423

Likes: 0

Bad noise coming from engine

I changed my cam and lifters awhile back and was going to replace the timing gears, but they were in good shape. They are the steel ones not the fiber gears so someone must have replaced them some time in the past. I still need to make a compression test but my Nissan PU bit the dust this weekend too. What a bummer

now all I have left is my single cylinder motorcycle to get around on.

Nov 6, 2002 | 04:31 AM

inliner

Thread Starter

Senior User

Joined: Jul 2001

Posts: 423

Likes: 0

Bad noise coming from engine

Well I pulled the head this week to check for a bent valve or sunken seats and instead found pieces of broken piston rings imbeded on the #2 piston. I was checking the other piston tops and found another problem. The #6 piston has a dish top and all the other pistons are flat-tops.:-staun Boy, some people have a weird way of rebuilding motors! It's no wonder this truck had a weird idle.

Nov 14, 2002 | 06:37 AM

ftwfred

Senior User

Joined: Nov 2002

Posts: 298

Likes: 1

From: Kentucky

Bad noise coming from engine

It is truly amazing what the Shadetree mechanic will do when there is no $$$$$ to be spent...
LOL

>Well I pulled the head this week to check for a bent valve
>or sunken seats and instead found pieces of broken piston
>rings imbeded on the #2 piston. I was checking the other
>piston tops and found another problem. The #6 piston has a
>dish top and all the other pistons are flat-tops.:-staun
>Boy, some people have a weird way of rebuilding motors! It's
>no wonder this truck had a weird idle.