Front Knock in Engine
09-13-2010, 08:41 PM
#1
Seasoned Member
Thread Starter
Front Knock in Engine
I have a slight knock in my engine near the front. I was told by a buddy it sounds like a bearing, but what bearing and is it an easy fix?
09-13-2010, 08:54 PM
#2
CF Veteran
Main or a Rod bearing,
Main bearing knocks can sometimes go away when you rev it up, they will also be more prevalent when you first start it.
A Rod is just that, a rod bearing is gone.
either way it is a big issue.
Best case scenario, crankshaft is not scored and you can just drop the pan and put a new bearing in it.
Worst case, the crank is scored and the engine has to come out to pull the cranks shaft and have it turned (lathe) down to .010 under side or more and replace all the bearings.
Main bearing knocks can sometimes go away when you rev it up, they will also be more prevalent when you first start it.
A Rod is just that, a rod bearing is gone.
either way it is a big issue.
Best case scenario, crankshaft is not scored and you can just drop the pan and put a new bearing in it.
Worst case, the crank is scored and the engine has to come out to pull the cranks shaft and have it turned (lathe) down to .010 under side or more and replace all the bearings.
09-13-2010, 09:02 PM
#5
CF Veteran
If your not experienced at this, I would suggest having an experienced mechanic listen to it.
its not really a job I would suggest you tackle alone if you've never assembled an engine before.
One thing you can do to help verify the sound origin, get a long extension or even a broom handle and with the engine idling, touch the oil pan, and with it and listen to the other end. Do the same for the side of the block, then move up to the valve cover and even the timing chain cover if you can get to it. Till the knock is the loudest.
If its loudest on the lower block or pan, its a rod or main knock, if its loudest at the timing cover its just timing chain slap (at least I think the 4.0 uses a timing chain instead of two gears) or if in the top of the engine from the valve cover you got a lifter tap going on.
its not really a job I would suggest you tackle alone if you've never assembled an engine before.
One thing you can do to help verify the sound origin, get a long extension or even a broom handle and with the engine idling, touch the oil pan, and with it and listen to the other end. Do the same for the side of the block, then move up to the valve cover and even the timing chain cover if you can get to it. Till the knock is the loudest.
If its loudest on the lower block or pan, its a rod or main knock, if its loudest at the timing cover its just timing chain slap (at least I think the 4.0 uses a timing chain instead of two gears) or if in the top of the engine from the valve cover you got a lifter tap going on.
09-13-2010, 09:07 PM
#6
Seasoned Member
Thread Starter
yeah Ive never assembled one before. ok ill try the broom handle trick to find out where it is for sure. excuse the ignorance whats a lifter tap?
a water pump knocking? thats strange. Ill definitely check to find out though. its not a bad knock at all you have to strain almost to here it. you cant here it while driving down the road
a water pump knocking? thats strange. Ill definitely check to find out though. its not a bad knock at all you have to strain almost to here it. you cant here it while driving down the road
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09-13-2010, 09:15 PM
#9
Seasoned Member
Thread Starter
rislone? ill look it up. I just changed my oil so itll be a good while beore I do that. yeah my oil pressure is always good.
09-13-2010, 09:17 PM
#10
CF Veteran
If your doing regular oil changes there is really no reason for rislone in the oil.
I officially against adding any of the master mechanics in a can in the oil.
The exception is when you know you've got an engine with lots and lots of buildup. this can be seen by looking in the valve cover fill hole. If its gummed up in there go for it. It it is not forget it.
If its that quiet a knock, it might be the very start of a bearing knock.
A lifter is the piece that rides on the camshaft, from there a push rod goes to a rocker arm, the rocker arm opens the valves.
The lifters use oil pressure to adjust the lash, when lifters go bad they bleed off the oil instead of taking up all the slack and make the rockers tap.
I officially against adding any of the master mechanics in a can in the oil.
The exception is when you know you've got an engine with lots and lots of buildup. this can be seen by looking in the valve cover fill hole. If its gummed up in there go for it. It it is not forget it.
If its that quiet a knock, it might be the very start of a bearing knock.
A lifter is the piece that rides on the camshaft, from there a push rod goes to a rocker arm, the rocker arm opens the valves.
The lifters use oil pressure to adjust the lash, when lifters go bad they bleed off the oil instead of taking up all the slack and make the rockers tap.
09-13-2010, 09:21 PM
#11
Seasoned Member
Thread Starter
ah gotcha. thanks for the information. That makes sense now. Yeah I just want to get this out of the way before it becomes a bad problem. you can only hear the knock when idling.
09-13-2010, 09:32 PM
#15
Seasoned Member
I had a deep knocking sound coming from the front of my engine once. It really had me concerned. Turned out to be the bearing in the water pump.
