Mechanics

ENGINE KNOCK, TIMING BELT

1996 Subaru Legacy

Engine Mechanical problem
1996 Subaru Legacy 4 cyl All Wheel Drive Manual 126000 miles

Greetings,
Thanks for your previous response on my 1988 jeep comanche. The fuel problem turned out to be the short link of gas line on the internal fuel pump. It had deteriorated to the point that even though the pump was pumping it was not creating enough fuel pressure. A $1 fix!

I have a 1996 subaru legacy. It has 126K miles. My son drives the car and he complained of some clicking noise. Upon examination I found several of the spark plugs loose. I assume this was because my son, after changing the plugs a few months ago, failed to touque them sufficiently. There was evidence of exaust gasses blowing by (blackened pocelain on plugs). One plug was missing the electrode. After replacing the plug and torquing all to about 20lbs, the engine ran great, no noise at all. After a few days of driving my son complained that there was more noise but worse. He stopped the car and we had it towed home. I checked it and the plugs were fine. I checked the compression thinking perhaps the missing electrode may have gotten stuck in the exaust valve. Compression was over 150 all around. I am now wondering what the noise is as it almost sounds like a connecting rod bearing gone bad. The timing belt was changed at around 70K miles. Could this be it? The engine starts easily and runs smoothly except for the knocking. There has never before been any hint of knocking and there is no indication that oil pressure is low. Any Ideas. What is next?
Thanks so much, Chris
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Surfjones
December 1, 2008.



Hi surfjones, I think you hit it on the money, the missing part of the spark plug must have become logged in the combustion chamber. To find out for sure remove the spark plug from the cylinder were you found the broken spark plug. Next, use a flash light to look inside of the spark plug hole. Rotate the engine by hand until you can see the top of the piston. You are looking for marks on top of the piston, indicating internal damage. If the piston looks ok, damage could have occurred to the rod bearing when the plug fell apart. Please let me know, thanks you using 2Carpros. Com

btw I featured this question on the home page! : -)

2CarPros Ken
Dec 1, 2008.
Thanks for the guidance. I looked for damage to the piston but I couldn't see any. Can I change the wristpin/bearing without pulling the motor? The knock is in the drivers side front cylinder. The shop manual indicates that the wrist pin can be removed through an access plug in the front of the block and the piston can then be pulled. Thanks, Chris
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Tiny
Surfjones
Dec 6, 2008.
Hi, unfortunately the once the engine starts making noise, the damage is already done, I don't think it is a wrist pin, but more of a rod bearing. The engine will need to be removed and repaired.

2CarPros Ken
Dec 7, 2008.

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