Matt Sullivan Posted July 1, 2003 Share Posted July 1, 2003 Might've over-revved my car (1992 VX Swindon 235) at RMA Bedford on Saturday. Result: Bad knocking sound from the nearside camshaft, which rises with the revs. Engine still runs and idles, though very badly. Spoken to Swindon, they reckon it could be a valve spring. They reckon its unlikely the valve hit the piston unless I REALLY over-revved it. Question: What am I looking for? I've taken off the cam cover, the shafts seem to be in good nick, and there's no loose pieces of metal! Cams are all present and correct and seem in good condition. Where do I go from here? Any advice greatly received. Technical ability usually stretches to changing pads and plugs. cheers, Matt. Link to comment Share on other sites More sharing options...
NickD Posted July 1, 2003 Share Posted July 1, 2003 Matt, Nasty noises and no visible damage probably means that the head will have to come off for inspection. You could run a compression test which would at least show if you have a badly seated (bent) valve anywhere. You can also see the exhaust valves if you remove the manifold so this might give further clues. Link to comment Share on other sites More sharing options...
EFA Posted July 1, 2003 Share Posted July 1, 2003 Matt, You'll almost certainly be looking at a head off job to fix it, so i suggest you do this first. Sounds like a broken spring which could mean valve/piston contact. I've got pistons and valves a plenty if you need some! Fat Arn Visit the K2 RUM website See the Lotus Seven Club 4 Counties Area Website here Link to comment Share on other sites More sharing options...
Alex Wong1697456877 Posted July 2, 2003 Share Posted July 2, 2003 Does the 235 spec have double springs? Take the cam cover off. Look at the cam buckets that are in the "up" position and press on them. If the valve spring is damaged, the one with the broken spring will be compressable with just a bit of pressure with a thumb. Turn the engine over by rocking the car forwards in gear and check the firmness on the rest of the cam buckets. I found this when I broke a spring and if one has broken, check the coressponding valve very carefully (Head off job). Mine looked ok but it didn't move very freely. Despite no obvious contact, the valve was bent. Edited by - Alex Wong on 2 Jul 2003 01:29:44 Link to comment Share on other sites More sharing options...
EFA Posted July 2, 2003 Share Posted July 2, 2003 235 = Single Springs Fat Arn Visit the K2 RUM website See the Lotus Seven Club 4 Counties Area Website here Link to comment Share on other sites More sharing options...
Matt Sullivan Posted July 2, 2003 Author Share Posted July 2, 2003 So if a spring goes, does that mean the valve drops? Therefore the knocking I heard was the piston pushing the valve up in to the cam bucket? Link to comment Share on other sites More sharing options...
Alex Wong1697456877 Posted July 2, 2003 Share Posted July 2, 2003 yes, until it's bent and then it's just the piston trying to knock the head off the valve.... ISTR that you can see some the springs with the cam cover off if you can look into the oil galleries. Link to comment Share on other sites More sharing options...
Alex Wong1697456877 Posted July 2, 2003 Share Posted July 2, 2003 If it's any consolation, when I broke a valve spring, it was pretty straight forward to replace it and the corresponding valve (with ECR's help, as usual). When I smashed up 8 valves and 2 pistons, it was a somewhat bigger job. 😳 Link to comment Share on other sites More sharing options...
Recommended Posts
Create an account or sign in to comment
You need to be a member in order to leave a comment
Create an account
Sign up for a new account in our community. It's easy!
Register a new accountSign in
Already have an account? Sign in here.
Sign In Now