I am working on 97 Prelude. I bought the car assuming it just had a blown head gasket. After i replaced the head gasket, I realized it was knocking.

I DON'T HAVE A VID CLIP!

My question is....

What are the most common cause of a knocking sound in the bottom end?

All input is appreciated.

TIA

Keith

 

spun bearing?

 

how about bad bearing?

No shavings in oil.

 

Come on Tech.

From your experience, What is usually the culprit for a knock?

Keith

 

ttt

 

help...

 

bearing or excessive clearance for the bearings...it's done, pull it out, and get a new one or rebuild it

 

So if the crank isnt screwed up , I can just replace the rod bearing?

 

sometimes, I have re-bearing'ed a motor that spun a bearing before...still in the car even, but generally speaking, once you've spun a bearing the motor should come out and go to a machine shop or be replaced

if you remove the oil pan, oil pump pickup and baffle you'll be able to get the the main and rod bearing caps, you can remove them one at a time until you've found the spun/screwed up bearing, and then check the crankshaft for any damage (if you can catch a finger nail on any mark its done) and decide then whether your going to re-bearing, replace, or rebuild

but if this is something you've never done before, I wouldn't recommend it, but then again I guess you really can't make it any worse than it all ready is

 

Im pretty sure the bearing isn't spun. There aren't any shavings in the oil pan. I have already pulled the pan, pickup, baffle, and bridge.

Then I removed the cap on the first cylinder...didn't see or feel any rough spots on the crank or bearing.

I can take a picture of the bearings if need be.

BTW: The oil in this engine mixed with the coolant completely. I was like grayish army green color. ( Don't know if this helps )

Thanks for your help.

Keith

 

you didn't change the oil after you did the headgasket? that's the only reason I can see for coolant in the oil other than a cracked sleeve

check all the bearings one by one...post a pic of anything suspect...also try to peek up into the cylinders to check for a cracked sleeve

if the oil was that mixed with coolant, that could be the cause of the knocking as well, could have thinned the oil out to the point that it knocked.

check all the bearings(mains and rods) one by one and re-torque to spec, if you don't find any bearings spun, or having excessive wear (post pics) then I would re-install everything, change the oil (10w30 or 10w40) and let her rip.

its possible that the coolant mixed oil is your problem (doubtful)

 

Could be a cylinder/ piston issue. If there are no shavings in the oil and there is a knock it could be a distorted cylinder wall, piston or even a wrist pin that suffered from a whole lot of heat when the head gasket blew. Is it loudest when cold? Out of curiosity did you do a valve lash adjustment after the head job? It wasnt mentioned in the previous posts. But if the motor gets a little quieter after its been warmed up then it would probably be a piston to wall issue.

 

sorry...

Yes I did change the oil after I replace the headgasket. But after running it for about 3min, then redraining it, It still looked a grayish color. ( Just not as bad)

Valve lash? I will check that.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by ekgcool &raquo;</TD></TR><TR><TD CLASS="quote">Could be a cylinder/ piston issue. If there are no shavings in the oil and there is a knock it could be a distorted cylinder wall, piston or even a wrist pin that suffered from a whole lot of heat when the head gasket blew. Is it loudest when cold? Out of curiosity did you do a valve lash adjustment after the head job? It wasnt mentioned in the previous posts. But if the motor gets a little quieter after its been warmed up then it would probably be a piston to wall issue. </TD></TR></TABLE>


That was what I thought. Maybe a wrist pin.

Im just trying the simplest things first.

It ran for about 3-5min, and never seemed to get any better.

Thanks for the help guys.

Keith

 

does it increase with RPM? if so it's a main and/or rod bearing, IF it's on the bottom. a wrist pin issue or cracked wrist pin boss will also increase with RPM, but that its in the top end, you'd hear is in a distinctly higher place than the crank area.
ring lands usually are not consistent in their sound, but can increase with rpm, but they, again, are up top.

the best idea is to take a long, BIG screwdriver or breaker bar/ pry bar, touch it to different areas from where you think the sound is eminating with your ear to the other end and hand cupped over your ear. you can tell when you are near the spot as it'll become very loud.

 

Thanks for your help man.

Keith

 

sounds like you could have a cracked sleeve if you are still mixing oil and coolant and your getting a knocking noise

have you checked all the bearings yet?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 92_civic &raquo;</TD></TR><TR><TD CLASS="quote">sounds like you could have a cracked sleeve if you are still mixing oil and coolant and your getting a knocking noise

have you checked all the bearings yet?
</TD></TR></TABLE>

The first time drained the oil there where water beads in it, with the icky grayish color.

After the head gasket, when I noticed the knocking, I redrained the oil. It didnt have the water beads in it then. It was just that grayish color.

When I dropped the oil pan, It had a lot of that gray sluge in it. I cleaned to pan for next time.

The only bearings I have out are the bottom main bearings, and the #1 cylinder rod bearings.

Keith

 

all the mains look good? can u post pics of any of this?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 92_civic &raquo;</TD></TR><TR><TD CLASS="quote">you didn't change the oil after you did the headgasket? that's the only reason I can see for coolant in the oil other than a cracked sleeve

check all the bearings one by one...post a pic of anything suspect...also try to peek up into the cylinders to check for a cracked sleeve

if the oil was that mixed with coolant, that could be the cause of the knocking as well, could have thinned the oil out to the point that it knocked.

check all the bearings(mains and rods) one by one and re-torque to spec, if you don't find any bearings spun, or having excessive wear (post pics) then I would re-install everything, change the oil (10w30 or 10w40) and let her rip.

its possible that the coolant mixed oil is your problem (doubtful) </TD></TR></TABLE>


<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by KeithsDAteg &raquo;</TD></TR><TR><TD CLASS="quote">sorry...

Yes I did change the oil after I replace the headgasket. But after running it for about 3min, then redraining it, It still looked a grayish color. ( Just not as bad)
</TD></TR></TABLE>

If it was grayish again after u replaced it and drained it again ur problem could be bigger than a bearing.^^

 

wouldn't you all think when I pulled the head I would have probably seen a cracked sleeve.

 

I would have checked your oil pressure before pulling the caps off to check bearings - if your engine is knocking from bearings you should see a decrease in oil pressure - I have seen loose flywheel bolts sound like a engine is knocking also - not likely but I'm just saying

 

Pics to come soon.

Keith

 

Here are some pics.

Sorry they are so shitty.

Give me your opinions.

 

looks pretty shitty to me man, sorry to say it, but from I can see those bearings are wiped out like you read about...how does the crank look?

 

Crank journals look good.

So... Can I plastiguage the old bearings to see if they are bad??

Keith