Phil1 Posted September 1, 2015 Report Share Posted September 1, 2015 I've recently fitted an Alloy rocker cover which is getting pressurised and spraying oil from the vent hole in the filler cap. Thinking of fitting an oil catch tank!! Phil. Quote Link to post Share on other sites
stuart Posted September 1, 2015 Report Share Posted September 1, 2015 Does it have a breather tube from the side of the cover? If not and depending if its a 4 or 4a engine does the block have a breather? Stuart. Quote Link to post Share on other sites
Mark1965TR4aBRG Posted September 1, 2015 Report Share Posted September 1, 2015 You'll be losing oil from the crankshaft 'seal' too.. Quote Link to post Share on other sites
john.r.davies Posted September 1, 2015 Report Share Posted September 1, 2015 Sorting the oil spitting from the cover is just bodging. You need to know why it's pressurising. Piston blow-by? John Quote Link to post Share on other sites
dbug Posted September 1, 2015 Report Share Posted September 1, 2015 Sorting the oil spitting from the cover is just bodging. You need to know why it's pressurising. Piston blow-by? John Agreed rocker cover shouldn't pressurise. As said there should be some sort of breather - is it there and if it is, is it blocked. A catch tank doesn't address the problem, merely masks it Quote Link to post Share on other sites
Phil1 Posted September 2, 2015 Author Report Share Posted September 2, 2015 Thanks for your replies. There's a breather on the engine block which is clear, no breather on the rocker cover. Quote Link to post Share on other sites
Mark1965TR4aBRG Posted September 18, 2015 Report Share Posted September 18, 2015 Piston blow by - as mentioned above - time for a rebuild. Quote Link to post Share on other sites
monty Posted September 18, 2015 Report Share Posted September 18, 2015 Piston blow by - as mentioned above - time for a rebuild. I would have thought the reason is no breather on the rocker cover. Put back the awful closed circuit system or breath into a Racetorations or TR Enterprises catch tank. The engine needs to breathe from block & rocker cover, in my experience. Cheers. Quote Link to post Share on other sites
Mark1965TR4aBRG Posted September 18, 2015 Report Share Posted September 18, 2015 ..all I can tell you is that my engine breathes hard through a vented rocker cover and it has blow by big time - hence my new engine! Quote Link to post Share on other sites
Motorsport Mickey Posted September 18, 2015 Report Share Posted September 18, 2015 Phil, You say you've only recently fitted the Alloy rocker cover, was the engine breathing when it had the tin rocker cover on ? and if not did you have any sort of rocker cover breather either into a valve or rebreathing through the carbs into the engine. Mick Rchards Quote Link to post Share on other sites
Allan Westbury Posted September 19, 2015 Report Share Posted September 19, 2015 I have also had this problem for a while and talked to Steve Hall of TR Enterprises about it at Malvern. I had fitted a catch tank but as other have said this only masks the problem. I was also pushing oil out of the dip stick and rear crankshaft seal as I have no breather on the crankcase. TRE do a breather kit that replaces the mechanical fuel pump but then of course you need to fit an electric pump. If you already have a breather I am suprised you have a pressurisation problem at the top. It can only be caused by piston blow-by which can be because your pistons/ rings are worn, you have a broken ring or as in my case you did not run the engine in after a rebuild. A compression test will show if you have a problem on just one pot in which case you probably have a broken ring. more than 1 pot down probably shows a worn engine. In my case I had good compression on all 4 which was baffling. Steve's view is that in the 5000 or so miles that I have done since the rebuild the liners have become glazed and the rings are not properly bedded in. The solution is to run for 500-1000 miles with a running in oil but not to 'cruise' at more than 3000 revs during the run in. Short bursts above that are not a problem. Hope this helps Quote Link to post Share on other sites
TriumphV8 Posted September 19, 2015 Report Share Posted September 19, 2015 If there is a breather that works correct somewhere at the engine and there is a problem with inside pressure the engine is damaged or worn. Something has to be done sooner or later where in addition the problem is that in most cases the modern ring development did not find its way into the 4 cylinder engines. Some big bore kits have smaller rings and 3 piece oil rings. Also hypereutectic pistons with much small bore to piston clearance are unknown. So to some extend the blowby belongs to the TR4 but on the other hand when it increases it reaches much earlier than a modern car acceptable limits. To avoid those problems at my V8 where more than two of the biggest TR4 engines blow by into one crankcase I used the Total Seal rings. They improve significantly but I do not know if they do that for TR4 engines. http://www.totalseal.com/ Quote Link to post Share on other sites
Geko Posted September 19, 2015 Report Share Posted September 19, 2015 (edited) i did away with the PCV and added a small K&N type filter on the rocker cover and another one at the fuel pump location. It breathes, stinks but doesn't leak, at least not from there. As for any TR if it breathes it leaks, so to speak... Edited September 19, 2015 by Geko Quote Link to post Share on other sites
john.r.davies Posted September 19, 2015 Report Share Posted September 19, 2015 The solution is to run for 500-1000 miles with a running in oil but not to 'cruise' at more than 3000 revs during the run in. Short bursts above that are not a problem. Hope this helps Suggest accelerating hard in as high a gear as possible without 'bogging down', then 'coast-down' with closed throttle. And doing it repeatedly, and as often as possible. The first forces the rings against the bores, and the second makes the vacuum as high as possible, to suck oil up into the bores to keep the rings lubricated. Should be done on first run after new engine start-up, but could be useful now too. John Quote Link to post Share on other sites
MichaelH Posted September 19, 2015 Report Share Posted September 19, 2015 The standard engine has a large 1" diameter breather in the block and the original flame trap from the rocker. If these or an equivalent size breather is not available the engine will blow out oil all over the place. I tried a smaller breather from the block to a catch tank and it blew oil out - when I replaced it with a 1"plus tube to the catch tank it stopped blowing oil out. Don't forget the flame trap has an element of vacuum as well from the intake manifold. Hence the advice to get big enough breathers. I suspect the ID of the vent in the ally rocker covers is not large enough Michael Quote Link to post Share on other sites
john.r.davies Posted September 19, 2015 Report Share Posted September 19, 2015 Another Point may be the run of the hoses from block to the catch tank. Recently I relocated the hose to run down, then up to to tank, and the tank filled with oil. It should run upwards, so that condensate can drip back into the sump. John Quote Link to post Share on other sites
stuartmac Posted September 20, 2015 Report Share Posted September 20, 2015 To avoid issues with the size of the rocker breather outlet how about running a 38mm silicone hose straight off the oil filler neck ( chrome rocker cover with push on type cap) Have a look at the sprite for sale on piston heads Quote Link to post Share on other sites
peejay4A Posted September 20, 2015 Report Share Posted September 20, 2015 Baffling to avoid oil splash down the pipe might be a problem. Quote Link to post Share on other sites
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