monty Posted September 24, 2006 Report Share Posted September 24, 2006 Hi All, Urgent help & advice needed! I have recently purchased a nicely restored TR4A & am finding my way around it. The engine appears to have a reasonable size leak at the rear which I think is the dreaded rear oil seal. I have read up all the points about this in the forums but still am somewhat confused! The car is booked in for investigation/rectification at my local performance car workshop (very good reputation/ex Formula 1 technician etc) & he is reasonably confident it can be cured with gearbox etc out. Reading the forums this appears not always certain! I do not really want to go to the trouble/expense of stripping engine to machine/regrind crank for an oilseal mod so do I try with an ordinary replacement (is it worth it?) or just leave the leak to drip on my garage floor & everywhere else! Any comments please. Regards, J. Quote Link to post Share on other sites
marvmul Posted September 24, 2006 Report Share Posted September 24, 2006 The TR4A has a crankcase ventilation system that should be in good working order. If not, this ventilation system can make the oil leak much worse. Quote Link to post Share on other sites
Ade-TR4 Posted September 24, 2006 Report Share Posted September 24, 2006 Hi not an uncommon problem by any stretch of the imagination! On a restored engine the oil pressure can be very high, this can force oil out of every seal going. Might be worth backing off the pressure a bit. Marvul is right re: crankcase pressure; the "4" engine is very long-stroked and builds up high case pressures. Again, a new build can be "tight" and enhance this effect. My own car has a drip-drip-drip (which has improved as the engine has bed in) and I've learned not to be worried about it. Andy's rally prep'd TR4 had the conversion and still leaked! I've heard good things about Halford's classic oil and its "Seall swelling" agent that apparently help stop leaks. Haven't tried it though. Has anyone had any experience? Cheers Ade Quote Link to post Share on other sites
tr3timme Posted September 24, 2006 Report Share Posted September 24, 2006 Hi, Monty: leaks at the rear of the 4/cyl. engine can, among other things, be caused by: a) failure of the square section felts at the back of the crankcase. To remedy this is a sump off - but not a gearbox out, job. It is a grubby, back-breaking task under the car, cutting sections of felt, soaking them in sealant and drifting them back up into their slot. But it can sometimes work. failure of the oil sealing plug/plate at the back of the crankcase, higher up. This is a g/box out and clutch/flywheel off job. It worked for my car a few years ago. You have to give the plug a good thumping with a hammer after insertion, to spread it and complete the sealing process. I, too, have heard mixed reports on the efficacy of the "improved" crankshaft oil seal. Good luck, Tim. Quote Link to post Share on other sites
monty Posted September 25, 2006 Author Report Share Posted September 25, 2006 Hi not an uncommon problem by any stretch of the imagination! On a restored engine the oil pressure can be very high, this can force oil out of every seal going. Might be worth backing off the pressure a bit. Marvul is right re: crankcase pressure; the "4" engine is very long-stroked and builds up high case pressures. Again, a new build can be "tight" and enhance this effect. My own car has a drip-drip-drip (which has improved as the engine has bed in) and I've learned not to be worried about it. Andy's rally prep'd TR4 had the conversion and still leaked! I've heard good things about Halford's classic oil and its "Seall swelling" agent that apparently help stop leaks. Haven't tried it though. Has anyone had any experience? Cheers Ade Hi Ade, Thanks for your comments. How do I back off the oil pressure? Monty. Quote Link to post Share on other sites
BrianC Posted September 26, 2006 Report Share Posted September 26, 2006 Monty, There are several discussion threads on the forum decribing how to adjust the oil pressure relief valve and it's not a difficult job. However, it's worth reading these thoroughly before doing anything, as opinions and experiences vary as to what the ideal oil pressure should be depending on temperature, engine speed and grade/type of oil used. Adjusting the relief valve without understanding the problem could make matters worse. Most TR engines leak and as long as the oil escapes and doesn't cause clutch slip, most of us live with it and consider it as automatic chassis preservation/rust-proofing. Quote Link to post Share on other sites
Kiwifrog Posted September 26, 2006 Report Share Posted September 26, 2006 I had this problem with a 4a a little while back. Being a good boyscout I used to keep the oil close to the top mark on the dipstick and it leaked a lot. After a while I gave up topping up the oil and when it had got to about 1/2 way on the dipstick the leak almost disappeared. After that I just made sure the oil level was about 1/2 way and the leakage was almost negligable! Quote Link to post Share on other sites
marvmul Posted September 26, 2006 Report Share Posted September 26, 2006 The oil pressure has no influence on the crankcase pressure and ventilation. The oil pressure is only maintained in the oil galleries, oil filter etc, but when the oil is escaping out of the bearings and into the crankcase, all pressure has gone. Especially the big end bearings throw around a lot of oil at a high speed. As everyone will have experienced : more rev's means more leaked oil. Quote Link to post Share on other sites
Ade-TR4 Posted September 28, 2006 Report Share Posted September 28, 2006 More revs also means higher pressure! Of course oil pressure doesn't affect crankcase pressure. A new build has poorly seated piston rings (until "run in"), this can allow blow-by of compression gases which will exacerbate the crankcase pressure problem. If your oil pressure is pushing 90-100 at higher revs, locate the big lock nut on the uppermost surface of the oil filter housing, unlock it and screw out the adjuster until desired pressure is acheived. hope this helps Adey Quote Link to post Share on other sites
ChrisR-4A Posted October 3, 2006 Report Share Posted October 3, 2006 Hi guys, when I purchased my 4A 10 years ago it had a bad oil leak from the bellhousing, investigations found the crankcase venting recirculating valve was in poor condition so on advice I removed it completly and vented the rocker cover direct to the atmosphere down below the carbs past the chassis. I also fitted the crankcase vent tube as used on tr4's which also vents direct and can be fitted with engine in place after removing the core plug. These mods stopped nearly all the leak , still a bit on some sump bolts but this has been reduced be removing bolts, cleaning with thinners and refitting with instant gasket. have done over 20000 since and car only uses about 1 pint oil a year in about 4000 miles. Chris Quote Link to post Share on other sites
ST TR5 Posted October 25, 2006 Report Share Posted October 25, 2006 Hi All, Got the crank out of my leaky engine again and I can't decide whether to put yet another traditional rear oil seal in or bite the bullet and get it ground to take a modern type I have hurd both and about fitting a modern seal, are there any that are better than others or is there only one type. I guess this will have been discussed at length in the past, but just looking for some upto date recomendations before I take the plunge. Cheers Sean Quote Link to post Share on other sites
tony-qld Posted October 25, 2006 Report Share Posted October 25, 2006 I replaced the old seal on my 4 with a modern type from one of the reputable Triumph suppliers and when the motor was assembled it leaked like a stuffed pig. I contacted the supplier and they sent me a new one straight away. The motor was yanked out and the seal replaced and now it doesnt leak at all. When I compared the first lip seal to the second one I was sent the first one was very hard and didnt have much flex in the rubber lip that sat gainst the crank. Maybe old stock. Quote Link to post Share on other sites
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