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Post by tedlit on Jul 21, 2015 3:11:21 GMT
Greetings, I have a dilemma with my P5. It's a mkii 3 litre coupe, and it smokes like a chimney. Perhaps a bit of back story.. I'm in the US - Oregon to be exact - and I bought this P5 not-quite-unseen a few years ago, largely to stop it from being scrapped. It had been stored since around 2001, but had been stored sorta-properly (on blocks, fuel system drained, fresh oil, etc etc). It turned over freely when I got it, and with most of a new ignition system it fired up first time. Good, even compression.. ticks a little when it's cranking, but that's just a chipped flywheel tooth... sounds and runs just fine when it's warmed up. The expansion tank being cracked at the seam was a nice discovery, but that's another story The problem is.. it does smoke rather. I've had the head checked out, and the machine shop swears blind nothing's leaking down the inlets into the combustion chamber.. and the crankcase ventilation system seems to be working just fine.. which I think means I'm left with badly worn rings as the only remaining cause. It's got 70k miles on it, and I've got no reason to believe that's not genuine.. but the problem is, the P5 is incredibly rare in the US so finding anyone to even look at a rebuild is a challenge in itself. Does anyone have any other suggestions? Is it possible to confirm blow-by for sure without dismantling things? Wondering how hard it is to stick the Rover v8 in there instead. I have an early P6 3500 for parts, but that's an auto and the P5 is a manual/overdrive.... and I really wanted to keep it original.  |
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Post by johnwp5bcoupe on Jul 21, 2015 5:40:23 GMT
Hi Russell what colour is the smoke? white? blue? or black? it may help with the diagnosis!
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Post by djm16 on Jul 21, 2015 6:05:10 GMT
Blow by the piston rings will lead to quantities of oily smoke coming out the crankcase breather and road draft tube.
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Post by Deleted on Jul 21, 2015 7:11:09 GMT
Get the engine hot and do a compression test.Squirt in a small quantity of oil in each bore and try a test again.The oil will temporarily seal the rings and the difference in readings will indicate how bad they are.Bear in mind too that worn lands in the pistons or rings that are too thin and can move up and down in the piston groves can work like miniature oil pumps and allow too much oil to work its way into the combustion chambers.
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Post by cstorey on Jul 21, 2015 8:47:28 GMT
Also, have a look at the plugs. The inlet over exhaust engine always had a tendency to use oil, and if it is rings then it is likely that you will see signs of contamination on the plugs. Also, on an engine that has stood for many years unused , the pistons/rings may be perfectly serviceable, but gummed with resinous deposits. One possible cure for this is to drain the sump, and fill each cylinder in turn ( with the piston at the top of stroke ) with cellulose thinners /acetone and leave it for 24hours for each cylinder . This may, only may, ungum things . Other possibilities - inlet valve guides
I wouldn't even consider putting a V8 in . It is much less refined than the 6, albeit more powerful , and does not have the same charm as the 6 cylinder car
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Post by Phil Nottingham on Jul 21, 2015 17:34:04 GMT
Our 3 Litre does 50 mpp and barely gives a puff of blue smoke. Worn piston rings are the problem not guides or leaks.
White smoke is most likely brake fluid from a failed brake servo (common) or steam from head-gasket or cylinder head crack
Black is carb set up
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Post by djm16 on Jul 22, 2015 0:02:56 GMT
OMG Phil, that is about a 20:1 mix. Even my 2-stroke chainsaw does better than that!  |
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Post by charlie on Jul 22, 2015 9:27:24 GMT
All p4 p5 burnt oil from new, [think of it as helping to keep the oil fresh] once i was shown a document from rover about oil consumption there estimate, can't remember what it was but remember thinking bloody hell thats high, maybe designed that way, i got a good stock of oil in and got used to it, and my personal choice would be a p5 burning oil than a p5b not burning oil, love the power of the V8 but it does not [in my opinion] come near the charm smoothness rolls- royce like character of the straight six, at end of day i suppose you need both but if it had to be a choice six pot every time, choose the mk11 and you also get the best seating of any p5/p5b.
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Post by Warwick on Jul 22, 2015 9:41:23 GMT
... love the power of the V8 but it does not [in my opinion] come near the charm smoothness rolls- royce like character of the straight six, ... Now there's a challenge for enigmas or petervdvelde. Take a pair of 3-litre blocks and make a 6L V12. They'd probably have to commission extra-heavy duty front springs from JRW. |
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Post by tedlit on Jul 22, 2015 16:49:04 GMT
Hi Russell what colour is the smoke? white? blue? or black? it may help with the diagnosis! Pure blue smoke - no hint of anything else. It doesn't smoke at all when its cold, but it gets worse as it warms up. Once it's warm, it smokes a little at idle but is pretty bad under load. The thing that makes least sense is that it's intermittent - it doesn't do it all the time. I've only done a cold compression test so far; it showed 135-140psi across the board. I fitted a new head gasket earlier this year as I had the head off anyway - and yes, it smoked in exactly the same manner before and after the head work. I've never heard another P5 3-litre running up close, so I'm not sure what it's supposed to sound like - but once it's started, it's reeeeeeally smooth! |
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Post by tedlit on Jul 22, 2015 16:58:12 GMT
Purely out of interest, here's what the head looked like when I removed it. Guess where the head gasket was gone.... Attachment Deleted ...and here it is the very first time it started. It looks like a misty morning, but no - that's a nice cloud of Rover smoke. Attachment Deleted |
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Post by Phil Nottingham on Jul 22, 2015 17:16:22 GMT
The Rover IOE 6 was designed as 1/2 a V8 perhaps a V12. Merlin?
The WW2 Rolls Royce tie up may have something to do with it but like their IOE6 used till 1959 in the S1 Clouds it is smooth torquey and exceptionally quiet even when quite worn. Even the then new V8 Rolls-Royce engine as with the Rover-Buick V8 there is really no contest as to silence/smoothness - the IOE6 are streets ahead.
It does seem to be piston rings/bores if it smokes badly when worn - they usually fume from the breathers too much. Check not blocked including the one under the inlet manifold.
Not a big job to convert to a P5B engine especially if engine, auto gearbox and subframe used but why not buy a V8 car instead. The 3 Litre subframe can be easily modified but the back axle ratio will be wrong for the P6 autobox.
I repeat mine does NOT smoke!
PS did you replace the head oil gallery/drain O ring at the back?
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Post by johnwp5bcoupe on Jul 22, 2015 17:19:49 GMT
Hi Russell what colour is the smoke? white? blue? or black? it may help with the diagnosis! Pure blue smoke - no hint of anything else. It doesn't smoke at all when its cold, but it gets worse as it warms up. Once it's warm, it smokes a little at idle but is pretty bad under load. The thing that makes least sense is that it's intermittent - it doesn't do it all the time. I've only done a cold compression test so far; it showed 135-140psi across the board. I fitted a new head gasket earlier this year as I had the head off anyway - and yes, it smoked in exactly the same manner before and after the head work. I've never heard another P5 3-litre running up close, so I'm not sure what it's supposed to sound like - but once it's started, it's reeeeeeally smooth! Follow Kev's post : Get the engine hot and do a compression test.Squirt in a small quantity of oil in each bore and try a test again.The oil will temporarily seal the rings and the difference in readings will indicate how bad they are.Bear in mind too that worn lands in the pistons or rings that are too thin and can move up and down in the piston groves can work like miniature oil pumps and allow too much oil to work its way into the combustion chambers. It may be a broken ring? having a good look at the bores, rings and pistons would be the way I would go  |
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Post by harvey on Jul 22, 2015 17:56:08 GMT
The 3 Litre has a couple of nice stablemates there.
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Post by johnwp5bcoupe on Jul 22, 2015 18:10:17 GMT
PS did you replace the head oil gallery/drain O ring at the back? It's a long time since I worked on my Mk2 and Mk3 Phil  looking at the PB is that the O ring fitted to Suffix C onwards? |
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Post by Phil Nottingham on Jul 22, 2015 19:29:10 GMT
Yes I think it is but will have to check
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Post by p5rover on Jul 22, 2015 19:37:17 GMT
Piston rings could possibly be sticking, I always put diesel fuel down the bores of any engine that has been unused for a long time.
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Post by tedlit on Jul 22, 2015 23:52:15 GMT
The 3 Litre has a couple of nice stablemates there. Thanks! The one on the left is a P6 3500S (NADA-spec, obviously) the one on the right is a Jaguar 420. The Jaguar is definitely the most "common" of the three - I've only ever seen one other P5 over here (a blue P5 sedan) in the last ten years...! |
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Post by tedlit on Jul 22, 2015 23:55:40 GMT
Follow Kev's post : Get the engine hot and do a compression test.Squirt in a small quantity of oil in each bore and try a test again.The oil will temporarily seal the rings and the difference in readings will indicate how bad they are.Bear in mind too that worn lands in the pistons or rings that are too thin and can move up and down in the piston groves can work like miniature oil pumps and allow too much oil to work its way into the combustion chambers. It may be a broken ring? having a good look at the bores, rings and pistons would be the way I would go I will absolutely give that a try. I did a cursory inspection of the bores etc when the head was off; aside from everything being kinda oily there was no obvious scoring or anything else untoward. I did initially think that the previous owner (owned car since mid-80s) discovered the engine was seized when he pulled it out of storage, and filled the bores with some sort of oil to free it up - with the resulting smoking-like-a-train-effect persisting - but he assured me it got turned over on a monthly basis and there's no other sign it was stored improperly. That said, force-unseizing an engine could certainly break a ring or two... ask me how I know. |
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Post by enigmas on Jul 23, 2015 0:00:48 GMT
Agree with all above. Considering its age, add glazed bores. Why not just bite the bullet pull the engine and re-ring it. If the piston lands are worn and it's usually only the top one have the piston machined for a wider ring. JP pistons in OZ will make a custom ring for $14 AUD. (Been there done this)
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Post by harvey on Jul 23, 2015 12:12:36 GMT
The 3 Litre has a couple of nice stablemates there. Thanks! The one on the left is a P6 3500S (NADA-spec, obviously) the one on the right is a Jaguar 420. The Jaguar is definitely the most "common" of the three - I've only ever seen one other P5 over here (a blue P5 sedan) in the last ten years...! I've owned a staggering amount of P6's, but never a NADA, and I've also had a M/OD 420 in Gunmetal with red leather. |
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Post by cstorey on Jul 23, 2015 13:33:20 GMT
It's actually a 420G ( i.e. late mark 10 ) which is a completely different animal from a 420 !
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Post by harvey on Jul 23, 2015 14:06:49 GMT
It's actually a 420G ( i.e. late mark 10 ) which is a completely different animal from a 420 ! I actually thought that when I looked at the pic, but couldn't be sure. It was just the camera angle which made me uncertain, so when the OP said it was a 420, who am I to argue? You don't see many Mk10/420Gs on wires. |
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Post by tedlit on Jul 23, 2015 16:21:59 GMT
It's definitely a 420; a 420G wouldn't fit in my garage. I'm hoping to get some time to dive back into the P5 this weekend. It's 100% rust-free, so it's definitely a car I'm keeping... and that I'm hoping to keep original. |
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Post by cstorey on Jul 24, 2015 9:29:03 GMT
It's definitely a 420; a 420G wouldn't fit in my garage. Oh - apologies - it was the chrome side strips which made me think it was a G, despite the wire wheels |
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looking at the PB is that the O ring fitted to Suffix C onwards?