Paul J Posted August 16, 2016 Report Share Posted August 16, 2016 Help again. I know this subject has been aired many times but there seems to be many variations of breathing covers. I have a vented cover with the vent in the top centre of the cover with a brass elbow feeding the hose to the diaphragm valve, the filler is also a vented cap (slide in with a mushroom containing chicken wire) which emits oil vapour on my new paintwork. Is there any reason not to fit a non vented oil filler cap and also fit an oil recovery bottle/tank. I note the new alloy covers are vented with a non vented cap so theoretically a solid cap in mine would achieve the same. Thanks Paul Quote Link to post Share on other sites
Geko Posted August 16, 2016 Report Share Posted August 16, 2016 (edited) Hi Paul, 4As don't have the odd-shaped crankcase breather on the engine block so you'll soon find out that blow-bys will start pushing oil through the dipstick hole; through the crankshaft rear seal or whatever soft spot if you do not have proper breathing system. Catch tank is one, engine block breather another. Edited August 16, 2016 by Geko Quote Link to post Share on other sites
Paul J Posted August 16, 2016 Author Report Share Posted August 16, 2016 Hi Paul, 4As don't have the odd-shaped crankcase breather on the engine block so you'll soon find out that blow-bys will start pushing oil through the dipstick hole; through the crankshaft rear seal or whatever soft spot if you do not have proper breathing system. Catch tank is one, engine block breather another. Thanks Stef, what I'm looking for though is the most effective solution. If there is one. Paul Quote Link to post Share on other sites
stuart Posted August 16, 2016 Report Share Posted August 16, 2016 Start with a proper 4a rocker cover as it sounds like you have either a 3a or early 4 one then either use a catch tank or the original PCV setup back into the manifold if you have the correct manifold. Stuart. Quote Link to post Share on other sites
RogerH Posted August 16, 2016 Report Share Posted August 16, 2016 +1 for Stuart Roger Quote Link to post Share on other sites
Paul J Posted August 16, 2016 Author Report Share Posted August 16, 2016 Start with a proper 4a rocker cover as it sounds like you have either a 3a or early 4 one then either use a catch tank or the original PCV setup back into the manifold if you have the correct manifold. Stuart. Hi StuartI seem to have a mismatch of parts for a 4A. Pic as is. Quote Link to post Share on other sites
RogerH Posted August 16, 2016 Report Share Posted August 16, 2016 Hi Paul, that is a TR4 cover and TR4a PCV. You need a TR4A cover. Roger Quote Link to post Share on other sites
Paul J Posted August 16, 2016 Author Report Share Posted August 16, 2016 Hi Paul, that is a TR4 cover and TR4a PCV. You need a TR4A cover. Roger Thanks Roger confirmed my thoughts. Next question does anyone have a spare 4A rocker cover that's surplus to requirements? Thanks all Paul Quote Link to post Share on other sites
stillp Posted August 16, 2016 Report Share Posted August 16, 2016 Surely all Paul needs to do is to fit a non-vented cap? Pete Quote Link to post Share on other sites
RogerH Posted August 16, 2016 Report Share Posted August 16, 2016 Hi Pete, sadly no. He does not have the TR4 breather pipe down by the fuel pump. His crankcase will pressurise and cause oil to come out of every orifice. He needs a 4A cover Roger Quote Link to post Share on other sites
RogerH Posted August 16, 2016 Report Share Posted August 16, 2016 Hi Paul, you have a PM Roger Quote Link to post Share on other sites
stillp Posted August 16, 2016 Report Share Posted August 16, 2016 Hi Pete, sadly no. He does not have the TR4 breather pipe down by the fuel pump. His crankcase will pressurise and cause oil to come out of every orifice. He needs a 4A cover Roger But he has a PCV. Doesn't that create a low pressure on the rocker cover? Pete Quote Link to post Share on other sites
Geko Posted August 16, 2016 Report Share Posted August 16, 2016 Thanks Stef, what I'm looking for though is the most effective solution. If there is one. Paul This is what I've done. But I have an electric fuel pump and deleted the PCV. Quote Link to post Share on other sites
peejay4A Posted August 16, 2016 Report Share Posted August 16, 2016 But he has a PCV. Doesn't that create a low pressure on the rocker cover? Pete I don't think so with that kind of filler cap/breather. The 4A cap has a very small hole so it allows a depression to form in the engine. Quote Link to post Share on other sites
stuart Posted August 17, 2016 Report Share Posted August 17, 2016 Yes a 4a cover is still required for it to work correctly, unfortunately I dont have one Paul. Stuart Quote Link to post Share on other sites
Paul J Posted August 17, 2016 Author Report Share Posted August 17, 2016 Thanks all so my understanding of this conundrum is Option 1. I get a 4A vented cover with a non vented filler cap and fit to the PCV valve as the system was designed with. Option 2. Leave as is and fit a engine block breather alongside or instead of the fuel pump. Option 3. Fit a non vented filler cap (with a very small hole) to the present rocker cover along with an oil catch tank. Option 1 seems to be the way to go as I will be returning the system to the way it was designed. If I have any problems then I will try an oil catch tank. Oil is a wonderful liquid as long as it remains where intended, I have spent so many hours/months over the years trying to achieve this. Thanks again all Quote Link to post Share on other sites
stuartmac Posted August 17, 2016 Report Share Posted August 17, 2016 whats the difference between the vented 4 cover currently installed, and the vented 4A cover (option 1) - will the current cover not accept an unvented cap? Quote Link to post Share on other sites
peejay4A Posted August 17, 2016 Report Share Posted August 17, 2016 (edited) The 4A cover has a twist on oil cap with a small hole in it which is under a small mushroom shaped piece. The 4 one shown has a push on cap/filter which allows much more air draw which is created by the snorkel tube or draft tube fitted adjacent to the fuel pump but blocked off on the 4A which has a PCV. The caps are very different and not compatible. Edited August 17, 2016 by peejay4A Quote Link to post Share on other sites
RogerH Posted August 17, 2016 Report Share Posted August 17, 2016 Hi Paul, email with pics on their way. Roger Quote Link to post Share on other sites
Bob Smith Posted August 17, 2016 Report Share Posted August 17, 2016 Paul, I have a spare 4a rocker cover - have sent a P.M. Quote Link to post Share on other sites
Paul J Posted September 4, 2016 Author Report Share Posted September 4, 2016 An observation follow up on this post. I collected a spare rocker cover and filler cap from Roger (not a sign of any headgear), the correct type to suit my closed engine breathing system. All fitted and good. The starting characteristics have now changed whereas before with the open filler cap full choke and no pedal I had instant ignition, now with the closed system I need full choke and 1/2 accelerator and not quite as quick a start. Not having instant ignition I feel is not so bad as it gives the lub system time to take effect. Not a problem, I was just surprised it changed things so much. Could you tell me what is the normal starting procedure cold and hot for other 4A owners. I believe the handbook states a hot engine no choke and third pedal. Quote Link to post Share on other sites
pascal33 Posted October 31, 2016 Report Share Posted October 31, 2016 Hello, I am a new (french) member. I have got a TR4A IRS (1967). On my car, I have the oil filler cap shown on the picture, but it is slightly broken. I am looking for it and I do not find the find it on internet.Please could tell me if one of us has that oil filler cap (running : not broken) ?Thank you in advanceBest regards.Pascal Quote Link to post Share on other sites
Don H. Posted October 31, 2016 Report Share Posted October 31, 2016 (edited) I don't recall a cap quite like that one, Pascal. Edit: It's been a lot of years since I had my TR350, but I sure don't remember that one being on it. Edited October 31, 2016 by Don H. Quote Link to post Share on other sites
BlueTR3A-5EKT Posted October 31, 2016 Report Share Posted October 31, 2016 Hello, I am a new (french) member. I have got a TR4A IRS (1967). On my car, I have the oil filler cap shown on the picture, but it is slightly broken. I am looking for it and I do not find the find it on internet. Please could tell me if one of us has that oil filler cap (running : not broken) ? Thank you in advance Best regards. Pascal That is the correct oil filler cap for a TR4A and supposedly TR250. It is a vented type rather than non vented type, which TR5/6 PI has. Use when a 'mushroom' shaped PCV valve is fitted/connected into the inlet manifold & breathing through a hoses to the rocker cover. Peter W Quote Link to post Share on other sites
BlueTR3A-5EKT Posted October 31, 2016 Report Share Posted October 31, 2016 (edited) That is the correct oil filler cap for a TR4A and supposedly TR250. It is a vented type rather than non vented type, which TR5/6 PI has. Use when a 'mushroom' shaped PCV valve is fitted/connected into the inlet manifold & breathing through a hoses to the rocker cover. Peter W PS give it a rinse with some type of degreaser fluid and refit. Edited October 31, 2016 by BlueTR3A-5EKT Quote Link to post Share on other sites
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