Johnny B Posted April 9, 2016 Report Share Posted April 9, 2016 Hi chaps , I have read various things about this subject on the forum previously but wonder if someone can explain in simpler terms . I have a 65 tr4 which has always had an oil leak which I had incorrectly assumed was the sump gasket . A proper examination has traced the majority of the issue as oil being forced past the dipstick felt when running. At tick over and no load seems ok just when higher revs or load when driving a large amount gets forced past. It doesn't appear overfilled , oil about halfway now between high and low mark. Rocker cover vents to pancake type filters with wire mesh on stromberg 175,s. Other articles have mentioned a build up of pressure in crank case but this is where I get lost. Can I , or do I need to relieve this pressure or am I miles away from the reason. Engine runs fine , pressure seems stable if I believe the gauge but everything seems normal . Oil dosent seem contaminated , no smoke on running etc .. Very grateful for suggestions and apologies if this is obvious ...John. Quote Link to post Share on other sites
stillp Posted April 9, 2016 Report Share Posted April 9, 2016 Which sort of crankcase breather do you have? Pete Quote Link to post Share on other sites
RogerH Posted April 9, 2016 Report Share Posted April 9, 2016 Hi Johnny, either the crankcase is pressurizing or it is overfilled. Do you know if your dip stick is actually correct? Remove all the breather pipes from the rocker and go for a drive se what happens. The pipes can block up. Have you got a PCV valve - this could be stuck shut. Roger Quote Link to post Share on other sites
TorontoTim Posted April 9, 2016 Report Share Posted April 9, 2016 re: dipstick being correct or not, do you know anyone nearby with a TR who you can compare yours with? (ooer...) If not, it's easy enough for me (or someone faster) to measure their stick from "shoulder" to markings and post result here, if you'd like to confirm. Quote Link to post Share on other sites
Bob Horner Posted April 9, 2016 Report Share Posted April 9, 2016 I had this - hoped it was blocked breatther, wrong felt washer on dipstick etc etc but in reality it was a tired engine with shot rings that simply fell off when the pistons came out! The crank case pressure resulting forcing oil out of the dipstick hole at anything other than tickover. The amount of oil that got pushed out was quite remarkable and looked like a serious oil leak with it dripping off the chassis after a high speed run. Bob Quote Link to post Share on other sites
littlejim Posted April 10, 2016 Report Share Posted April 10, 2016 (edited) Sorted bob!! And the info might help some of us if/when we get the same problem. Edited April 10, 2016 by littlejim Quote Link to post Share on other sites
Johnny B Posted April 10, 2016 Author Report Share Posted April 10, 2016 Hi, thanks for replies so far. I believe some engines had a breather/ vent from the block near the fuel pump, I don't have this. As far as I am aware My only venting is from the rocker cover via tube to the filters . I don't have a PCV. The rocker cover is after market alloy type Similar dimensions and vent hole as chrome original type . Filler cap not breathing? Seems air tight to me I guess it's not in practise. Dip stick measures 130mm from flange bit that felt sits in to higher mark, 160mm to lower. Bobs description seems similar to my expierence , engine was rebuilt 5 years ago and has seen very little use since but appears to have been maintained well, clearly I can't vouch for the rebuild. I just would have expected more obvious "bad" running symptoms if the rings were shot. Not science I know. I will disconnect vents from air filters as Rogers suggestion and try a run with a clear tube just from the rocker cover venting to the road See if I get a similar build up from dipstick hole. Can any of this be related to the oil pressure relief valve housed in the filter or is that something completly not connected? Again thank you for help ...John. Quote Link to post Share on other sites
john.r.davies Posted April 10, 2016 Report Share Posted April 10, 2016 (edited) Pi engines had no engine-driven mechanical fuel pump, and so the opening in the block was blanked off by a bolted plate, It wasn't used as a vent An additional cause of blockage over Roger's list would be a droplet trap inside the rocker cover, over the vent tube. A matchbox sized metal pressing spot welded onto the cover, was filled with wire wool to catch droplets of oil. Over the years the wool get filled up with gunge, and foils any attempt to free things up down stream. The boxes corners are open, to allow the condensed oil to drip back in, so probe with a fine screwdriver or hooked wire and pull out all the wool and gunk. Before you try his, disconnect-everything test, pull off the oil filler cap with the engine running. There should be a gentle zephyr of a breeze, of normal blow by coming out. If there is a mighty rushing wind, then you have excess blow by. John Edited April 10, 2016 by john.r.davies Quote Link to post Share on other sites
Geko Posted April 10, 2016 Report Share Posted April 10, 2016 The 4A vented filler cap helps a lot solving those issues. Quote Link to post Share on other sites
ChrisR-4A Posted April 10, 2016 Report Share Posted April 10, 2016 (edited) Hi John, the TR 4 should have a pipe about 1 inch dia fitted to the Block just below the fuel pump and held by a bracket onto one of the sump bolts. This was discontinued on the 4A when the PCV valve venting the rocker cover to the air filters was fitted. With just a vented cap it is not surprising there is a build up of pressure . If you have a later block as 4A then the hole for the vent pipe is blanked off with a core plug, this can be removed with the engine in the car by drilling a hole in the plug to then prise it off. A dremmel or an angle drill will just fit in. I did my 4a some years ago and I run the rocker vented to the ground, no PCV valve and a TR4 big pipe from the block. You should be able to pick a second hand pipe up from one of the usual suspects. Chris Edited April 10, 2016 by potts4a Quote Link to post Share on other sites
Bob Horner Posted April 10, 2016 Report Share Posted April 10, 2016 My TR4 (a late one) has the same arrangement as the TR4a - ie vented via the carbs and burnt. Contemplated the spew it on to the road arrangement of earlier TRs but went for catch tank instead (vented at the rocker and out of the old hole in the block) but it didnt help! But as i said, the truth was that the engine, although apparently healthy (good oil pressure etc), was blowing through the rings. You dont realise just how well a wet liner engine can go if rebuilt and balanced! Most of us only ever drive one TR and cant really tell how fast they can go or how well they can handle. I hope your engine is in better nick but if its really spurting out of the dipstick, unless there is a very obvious blockage, it may be time to enjoy a rebuilt engine!! Bob Quote Link to post Share on other sites
Johnny B Posted April 10, 2016 Author Report Share Posted April 10, 2016 Thanks all . Chris my 4 was built Nov 64 and has no vent fitted to the block , I can see the core plug below the fuel pump. Are you saying all 4 , s had the vent on the block ? I do have the vent from the rocker cover to the air filters on the strombergs . I assumed the later cars made do with this however I have no pcv or filter trap just a straight rubber hose to a tee piece then to the filters . I will experiment further in increasing the vent to the top end first as per the previous suggestions and see if it reduces it the problem. Quote Link to post Share on other sites
Johnny B Posted April 10, 2016 Author Report Share Posted April 10, 2016 Bob , I think you may be right , I may be kidding myself . Not the first time . John . Quote Link to post Share on other sites
ChrisR-4A Posted April 10, 2016 Report Share Posted April 10, 2016 Hi John , Bobs previous post suggests that some 4s were built as 4As. We all live and learn. Still you cannot have too much breathing, it all helps the engine run free er. Chris Quote Link to post Share on other sites
Johnny B Posted April 10, 2016 Author Report Share Posted April 10, 2016 Txs Chris . My search for originality went out the window when I decided that I would rather drive it than look at it. Whatever it takes to get it running is fine with me and slowly but surely more mods take place that take it further away from how it left the factory. Appreciate all the feedback will as I said attempt the freeing of the breathing first . An Engine rebuild will lead to so many other things that "may as well be done " scares me to death . I just want to drive it !!.. John . Quote Link to post Share on other sites
barkerwilliams Posted April 10, 2016 Report Share Posted April 10, 2016 John, Originality. Whatever you take off the car and replace, spray with chain oil (thick & sticky) put in a plastic bag and seal with one of those snaps. When you come to sell the car a prospective buyer may be put off by your newer mods but all the original parts he can refit after refurbishment might swing the deal. Alan Quote Link to post Share on other sites
Steve Priest Posted April 11, 2016 Report Share Posted April 11, 2016 Dip stick measures 130mm from flange bit that felt sits in to higher mark, 160mm to lower. Hi John, Out of interest I measured the dipstick on my TR4. It's approx 146mm to the upper mark and 177mm to the lower mark. Suggests that my oil level is about 16mm lower than yours when at the maximum level. Steve Quote Link to post Share on other sites
TorontoTim Posted April 12, 2016 Report Share Posted April 12, 2016 Sorry for the delay - I agree with Steve on dipstick measures. Might be worth, in conjunction with a number of other things you are trying, filling only to the bottom mark on your dipstick and run a test. Quote Link to post Share on other sites
Johnny B Posted April 12, 2016 Author Report Share Posted April 12, 2016 Steve/ Tim , interesting , Txs for measurements . Haven't had a chance for test yet but that's clearly different . Has had a recent oil change so could be overfilled . May drain and fill as per the workshop manual . Thanks again Quote Link to post Share on other sites
Johnny B Posted April 14, 2016 Author Report Share Posted April 14, 2016 Ok. Got somewhere. When the closed circuit breathing was disconnected on a test run the issue was cured, further investigation showed the tee place on the bracket of the carbs that splits the tube from the valve cover to the filters was completly blocked. I hadn't really considered that part could get blocked , although thinking about it now I'm not surprised. I also think my problem was magnified somewhat but running to full of oil. On a related note I can't seem to find replacement closed circuit type air filters , that are on the strombergs so I might as well ditch the closed circuit breathing I think , Get normal filters for the carbs and vent the valve cover directly out by below the engine. Shame to lose the original type filters but the inners appear to be some kind of non servicable wire mesh which I'm sure could be soaked in petrol or such but I'm not sure are up to the job. Thanks for all your help and suggestions makes this a lot easier. John. Quote Link to post Share on other sites
stillp Posted April 14, 2016 Report Share Posted April 14, 2016 Don't throw the old parts away! Pete Quote Link to post Share on other sites
Johnny B Posted April 15, 2016 Author Report Share Posted April 15, 2016 Pete, I hear you! Not intending to offend the members in search of originality , when I set out on this project I was determined to reproduce as near as I could to a TR that was as it was when it left the factory. I was helped by the fact that my starting point had not been molested to much . However certain components , in my mind at least , just don't hold up to frequent use. I'm keeping every original component that I replace in this way and the project for the winter months will be to restore these back to servicable use. The way I'm going I will then have enough parts to start on the next car! Priority 1 at the moment remains getting current vehicle to go more than a week without me having to rebuild something! Quote Link to post Share on other sites
stillp Posted April 15, 2016 Report Share Posted April 15, 2016 Good thinking Johnny. If nothing else, you'll be able to support your pension with ebay sales in your sunset years... Pete Quote Link to post Share on other sites
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.