Peter Watkins-Groves Posted July 31, 2019 Report Share Posted July 31, 2019 Hello, My Vitesse engine Gentry has a problem on number 6 inlet valve. after only a few miles the valve is sticking open due to a thick tarry carbon build up. All other cylinders look okay except for normal carbon that I would expect after more miles. I have checked the carbs (Stromberg cd150s) and they seem to be in tune. Could the emission valve be allowing too much oil into the inlet manifold. the car has newish valve guides and valves. Any suggestions. Link to comment Share on other sites More sharing options...
Guest Posted July 31, 2019 Report Share Posted July 31, 2019 Hello Peter, If the EV was allowing too much oil to slip through I would expect other valves to be affected - rather than number 6 being singled out. I wonder if the issue lies elsewhere, as in the oil control ring on that piston not doing its job properly, hence the carbon build up ?? Are you burning any smoke on start up or overrun ?? It will be worth treating the car to a dose of Redex directly in to the cylinder head to assist getting rid of deposits and that oil build up; may I suggest you do this in a fairly unpopulated area of the UK !! From there a compression test will be beneficial to ascertain if there is an issue on cylinder 6. As you say it may well be the EV, but I think the problem may be greater than that. Good luck. Richard. Link to comment Share on other sites More sharing options...
Pete Lewis Posted July 31, 2019 Report Share Posted July 31, 2019 Do not see the emmission valve being a problem , its only breather fumes no solids You,dont have a external oil feed flooding the rockers as this sounds more like a valve guide problem than breathers Pete Link to comment Share on other sites More sharing options...
Guest Posted July 31, 2019 Report Share Posted July 31, 2019 Yes that's a good call Pete, as the external feed is at number 6 end IIRC. It will be poor news if the valve guide is the issue, especially as the guides are newish according to the original post. Regards. Richard. Link to comment Share on other sites More sharing options...
Ben Caswell Posted July 31, 2019 Report Share Posted July 31, 2019 Has the location screw come out of the rear rocker post?? https://content.invisioncic.com/r252473/monthly_2019_07/FB51F9F1-5B17-46F8-A341-BDBC06AE55CC.MOV.e86d20e197e50f72d228017b68bf8b80.MOV Link to comment Share on other sites More sharing options...
Peter Watkins-Groves Posted August 1, 2019 Author Report Share Posted August 1, 2019 Cheers fellows for the replies. The engine had been rebuilt before I got the car, but hadn't run for some 30 years since rebuild. The guy that was rebuilding the car died mid-way, and it stood in a barn from the 90s till I bought it in 2017. Sorting out what has been done and what hasn't has been a major task, but it is obvious that the engine was re-bored and new pistons fitted, valves and guides were also done, don't know about bottom end yet, so fingers crossed there. There is no extra oil feed. I have been half thinking of stuck rings, but at 72 didn't relish the thought of lying on my back and dropping the sump to find out. I have the head off at the moment as I have to clean up the valve area, when that's done I will do what I should have and test the compression on all cylinders. There used to be a product that you could buy that supposedly un-gummed sticky rings, can't remember the name, and I doubt that it was very affective, but will give the Redex idea a shot before I put the head back on, can't hurt. I did drain the old oil, and used a flushing oil to clean out the crappy build up of old emulsified gunge. Thanks again, will keep you posted. ps: Saw your club stand at Grimsthorpe/Baston car show and was impressed as you have a Peterborough section. May have to change allegiances. Link to comment Share on other sites More sharing options...
johny Posted August 1, 2019 Report Share Posted August 1, 2019 As I understand it the valve guides are reamed when replaced to get the correct tolerance fit to the valve and of course its possible to leave it too tight so that it sticks as it warms up. Think this sounds more likely than carbon build up.... Link to comment Share on other sites More sharing options...
Pete Lewis Posted August 1, 2019 Report Share Posted August 1, 2019 if i remember on the old lost forum the brass type of guide had a lot of sticking problems giving problems on what was thought to be an upgrade but turned into chaos not had the experience myself but while the heads off what type of guides are fitted ??? pete Link to comment Share on other sites More sharing options...
Peter Watkins-Groves Posted August 1, 2019 Author Report Share Posted August 1, 2019 27 minutes ago, johny said: As I understand it the valve guides are reamed when replaced to get the correct tolerance fit to the valve and of course its possible to leave it too tight so that it sticks as it warms up. Think this sounds more likely than carbon build up.... I must admit No6 inlet may be a little closer in tolerance than the others. But it is sticking on the tarry carbon build up I think. Link to comment Share on other sites More sharing options...
Peter Watkins-Groves Posted August 1, 2019 Author Report Share Posted August 1, 2019 3 minutes ago, Pete Lewis said: if i remember on the old lost forum the brass type of guide had a lot of sticking problems giving problems on what was thought to be an upgrade but turned into chaos not had the experience myself but while the heads off what type of guides are fitted ??? pete I all ways used bronze guides on my motorcycles because they held oil better. Link to comment Share on other sites More sharing options...
Colin Lindsay Posted August 1, 2019 Report Share Posted August 1, 2019 21 hours ago, Peter Watkins-Groves said: after only a few miles the valve is sticking open due to a thick tarry carbon build up. Just to clarify, Peter - is it tarry or sooty? This one was - I think - caused by an overrich mixture but the deposits seem drier and more powdery than tarry; how does this compare with yours? Link to comment Share on other sites More sharing options...
Peter Watkins-Groves Posted August 1, 2019 Author Report Share Posted August 1, 2019 1 hour ago, Colin Lindsay said: Just to clarify, Peter - is it tarry or sooty? This one was - I think - caused by an overrich mixture but the deposits seem drier and more powdery than tarry; how does this compare with yours? It's tarry Colin, but only that valve is affected as bad. Pretty certain its not the guide, if anything that is a close fit. I am leaning toward "Classiclifes" idea of gummed oil control ring on that cylinder. Link to comment Share on other sites More sharing options...
Peter Watkins-Groves Posted August 1, 2019 Author Report Share Posted August 1, 2019 2 hours ago, Peter Watkins-Groves said: I all ways used bronze guides on my motorcycles because they held oil better. The valves fitted are standard steel/iron. Link to comment Share on other sites More sharing options...
RogerH Posted August 1, 2019 Report Share Posted August 1, 2019 26 minutes ago, Peter Watkins-Groves said: It's tarry Colin, but only that valve is affected as bad. Pretty certain its not the guide, if anything that is a close fit. I am leaning toward "Classiclifes" idea of gummed oil control ring on that cylinder. Hi Peter, if it is the 'piston oil control ring' how is the excess oil getting to the back side of the inlet valve. It doesn't. The only way is either down the valve guide or in through the carbs picking up oil from where ever. Roger Link to comment Share on other sites More sharing options...
dave.vitesse Posted August 1, 2019 Report Share Posted August 1, 2019 What state is the No. 6 plug in, as plugs are a good indicator of any oil present. Dave Link to comment Share on other sites More sharing options...
Peter Watkins-Groves Posted August 1, 2019 Author Report Share Posted August 1, 2019 35 minutes ago, dave.vitesse said: What state is the No. 6 plug in, as plugs are a good indicator of any oil present. Dave Sooty Dave but not sticky tar. Plugs indicate a slight richness which maybe because with the change of body to RMB Gentry style, little or no room is left for an air filter. So to combat a tendency to weakness through only having mesh filters fitted, I set the carbs on the rich side. Link to comment Share on other sites More sharing options...
johny Posted August 1, 2019 Report Share Posted August 1, 2019 Could you have an excessively weak spring on that valve? Link to comment Share on other sites More sharing options...
dave.vitesse Posted August 1, 2019 Report Share Posted August 1, 2019 Peter, I guess it must be a small amount and burning it off. Just a though, it's not oil from the air filters ? Though it does sound as if it could be a valve guide. Dave Link to comment Share on other sites More sharing options...
Pete Lewis Posted August 1, 2019 Report Share Posted August 1, 2019 odd thoughts , its seems to be collecting when the valve is closed. and why is it not burning off when hot exhaust passes. is the valve lifting fully ??? pete Link to comment Share on other sites More sharing options...
RogerH Posted August 1, 2019 Report Share Posted August 1, 2019 Hi Pete, from the first post it is an inlet valve - no hot gases as such. Roger Link to comment Share on other sites More sharing options...
Pete Lewis Posted August 1, 2019 Report Share Posted August 1, 2019 senior moments ...creep in everywhere pete Link to comment Share on other sites More sharing options...
Peter Watkins-Groves Posted August 2, 2019 Author Report Share Posted August 2, 2019 Thanks for all the suggestions and advice. I have decided it is a tight fitting inlet valve and have lapped the valve in the guide to give a few 10ths extra clearance. As I said at the start, the valves and guides were fitted 30yrs ago but never run in. So it will be finger in the Link to comment Share on other sites More sharing options...
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