CRXBart

Ok a couple of weeks ago I let a friend drive my car. I had been driving it realitivly hard the entire weekend so I suppose anything was possible. I noticed it sounded a little bit louder than usual when he departed. Yes a dreaded knock sound from under the hood. I didn't think anything of it but I drove home without the radio, when he got back. It was definitly knocking pretty bad a low rpm. Not horrible but pretty bad.

Disgusted I have just know decided to investigate. It sounds like it is comming from high on the motor, like the cylinder head. I decided to adjust the valves and elimnate that possiblity. That did jack. they were out of adj. but the noise is still present.

My question is, is there anything in the head that could be bad? Like a worn out valve seat or something? It still has good power and pulled good on the way home that night. It didn't seem to be lagging at all.

Or to my dismay is the bottom end toast? That would actually be to my liking for I have several B18A long blocks and only one vtec head.

Basicly has anyone ever had the mechanical **** inside of their head fail? When I rebuilt the motor 2 years ago I left the factory bearings, and valve seats in because the valves felt fine, and the bearings hardly showed signs of wear. The sound defintly sounds like it is coming from the upper quadrant of the engine, thats what baffles me. Every other honda I've smoked I killed bottom end bearings and it lost power and ran like ****. Then blew. This sounded totally different.

BTW I should have replaced the valve seats it still smoked after engine compression breaking after the rebuild. That leads me to beleive it could be valve seats. Is it possible?

Thanks any help appreciated.

Jared

I bet its a rod knock. They always tend to sound like they're in the top end. Pull individual plug wires with the engine running one cylinder and a time and you should be able to isolate it to a cylinder.

RCautoworks

How bought the lost motion assemble ? When they fail they tend to cause a knocking sound. How bad of a sound is it by the way ? Does it sound like valve chatter at all ? The injectors on Honda's are also known to cause a ticking noise but it sounds to me like the sound your hearing is a little louder then the injector tick. I would look into the lost motion assemble. Also does the sound seem to go away when rpm's rise ?

civickiller

rod bearing gone. i just got my ls started up a few weeks ago only to hear a really loud knocking sound which turned out to be the #1 rod bearing was gone

CRXBart

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 90blackcrx &raquo;</TD></TR><TR><TD CLASS="quote">How bought the lost motion assemble ? When they fail they tend to cause a knocking sound. How bad of a sound is it by the way ? Does it sound like valve chatter at all ? The injectors on Honda's are also known to cause a ticking noise but it sounds to me like the sound your hearing is a little louder then the injector tick. I would look into the lost motion assemble. Also does the sound seem to go away when rpm's rise ?</TD></TR></TABLE>

Yes it does seem to go away when it is reved up. Yeah it is a knock sound not a tick. It isn't too bad, but bad enough for me not to drive it and f_ck it up worse. It doesn't really sound like valve chatter it is more of a knock.

RCautoworks

Well I have had people tell me they had a rod knock and it really turned out to be the lost motion assemble. And since you said it does go away the higher the rpms makes me think its the lost motion assemble. Last time you drove it, can you remember if the sound went away or decreased when vtec kicked in ? If so then that would be a sign its the lma.

CRXBart

I'll trow the valve cover back on and give that a try. Thanks alot man. Can you just buy a new LMA from honda? I would assume so, but I thought they were head specific. So will it require machining? Thanks alot any help on this topic is greatly appreciated.

RCautoworks

Your welcome, I suppose you can get lma's from Honda, I would try ebay first actually. It don't have to be machined but it does take some work getting the new ones in and the old ones out. I have also heard another way of testing the lma, you just push on the center rocker arm , and if it pushes back its not the lma thats bad. I found this write up from 88dxcrx, hope he don't mind me posting it.

Do you have the "vtec supplement"?
If not ,you can download it at
http://www.acute.f9.co.uk/crx/...s.htm
{It is in adobe acrobat which is kind of a pain..}But after you download it
-Print out- pages 5-49 and 5-50 (much easier to read that way)..
basically you must remove everything in
picture 5-49 in addition to the distributor(if the bad LMA is on the intake side)...
and/or the spool valve if the LMA is on the exhaust cam and thats the easy part...
If you are only replacing one "LMA" as opposed to the whole set,you will only have to remove the camshaft that is ajacent to the LMA you are replacing.
Now for the fun part..The rocker arms in sets of threes are mounted on a
rocker shaft and must be removed before the LMA will come out; after you remove the oil control orifices and "searing bolts"See page 5-50,These are on both the passenger side and the drivers side of the head,the rocker shaft will slide outward,For the front rocker shaft I had to unbolt the drivers side mount and jack up the engine slightly so that the shaft would clear the mount.I had to slide the shaft to the right side to get at two of them and then side it out the left side to get at the other two.{The rear set was slightly easier}I will probably pull my valve cover back off in the next day or so and I will take some pics for you..
Now that I have totally confused you...any questions?
I spent probably 3-4 hours doing it,but it was well worth my time...

CRXBart

Cool thanks alot for the info. I also failed to mention I have CTR cams in my B16. I did a search on the lost motion assembly and found lots of people have had problems with LMA and larger cams. I figure that could have caused the problem. Also I assume this is a given, Yes, but I'll ask anyway. Will it f_ck stuff up if I drive it like this? I haven't driven it except for the ride home once I noticed it, just wondering if it could cause more problems down the road. Thanks again.

RCautoworks

If you drive it and don't beat the **** out of it, you will be fine. Just try to keep the rpm's down.