Graham King Posted November 16, 2018 Share Posted November 16, 2018 Folks, any help appreciated here as I’ve done almost everything I can think of to diagnose this and before I embark on an expensive route to resolve I want to see if there is anything else I can do.I have a 1999 Superlight with a 1.8K VHPD that was originally built for by DVA approx 8-10 years ago. It has BP285H cams, forged pistons and a ported VHPD head. About 4 years ago I had the valve stem seals replaced as they were leaking oil, at the same time the piston rings were replaced. This work was done by BOSS Racing (as they are fairly local to me). The engine has always run really well and continues to do so. But it has always had a liking for oil but recently this has got to the stage that I need to do something about it. As an example I took the car down to Le Mans last year, a return journey of approx 750 miles, for that journey the engine required approx 1.5L of oil. I have checked everything that I can easily check, the spark plugs are nice and clean (when I had the valve seals replaced the plugs were oily), there are no leaks, there is no visible smoke on start up or whilst running. I’ve done a compression test and all cylinders are similar at 240 so they look good. One other point to note is that the oil itself is pretty black when checked on the dipstick, I remember in the past having trouble reading a level on the dipstick. I’ve read a lot (prob too much) about glazed bores causing this type of issue, is there anyway I can rule this in or out, bore scope maybe?Has anyone got any ideas of any further checks I can do myself or any ideas as to what else may be causing it before I have to hand it over to one of the experts? Appreciate any thoughts.Many Thanks.Graham. Link to comment Share on other sites More sharing options...
rj Posted November 16, 2018 Share Posted November 16, 2018 You could have a leak down test done. Link to comment Share on other sites More sharing options...
Graham King Posted November 16, 2018 Author Share Posted November 16, 2018 Rj, thanks for the reply, I’ve heard of leak down tests, they appear to be a compression test in reverse. If I had one done, what would it tell me? Is it something my local garage would be able to do or is it more specialist?CheersGraham Link to comment Share on other sites More sharing options...
Paul McKenzie Posted November 16, 2018 Share Posted November 16, 2018 After the ring change, did you run it in on synth or semi-synth, and for how long? Link to comment Share on other sites More sharing options...
Graham King Posted November 16, 2018 Author Share Posted November 16, 2018 Hi Paul, it was run in on mineral oil for approx 500 miles, I know there are differing opinions on how to run an engine in, I did mine gently, increasing the max revs after each 100 miles starting at 3000 for the first 100 miles. Link to comment Share on other sites More sharing options...
Paul McKenzie Posted November 16, 2018 Share Posted November 16, 2018 Hi GrahamHead off or borescope would be the way Link to comment Share on other sites More sharing options...
simon_h Posted November 16, 2018 Share Posted November 16, 2018 I suppose a question would be why we're the rings replaced? In the past with a re-ring wouldn't the bores have been glaze busted to help the new ones bed in. Maybe this needed doing as well and as result they have never managed to properly bed in. Link to comment Share on other sites More sharing options...
rj Posted November 16, 2018 Share Posted November 16, 2018 The leakdown test would tell you if the rings don't seal properly. I don't know who can do it - I've made my own stuff to test with. Link to comment Share on other sites More sharing options...
Graham King Posted November 16, 2018 Author Share Posted November 16, 2018 The rings were replaced by BOSS when they did the seals as when checked them they said they were out of tolerance so whilst they had the engine with them they replaced them anyway. I don’t know for certain but I’d be pretty confident that they did hone the liners again as they are very experienced at rebuilding engines in general and have done a number of k-series. RJ, I’ll have a word with my local friendly garage to see if they have the relevant equipment. Doesn’t a compression test check the seal of the rings? Link to comment Share on other sites More sharing options...
Wrightpayne Posted November 16, 2018 Share Posted November 16, 2018 Surprised Mr Revill not chipped in yet following his painful journey building his engine, was it 3 or 4 times?Long thread on this in the archives from not too long ago.Ian Link to comment Share on other sites More sharing options...
revilla Posted November 16, 2018 Share Posted November 16, 2018 I spent two years chasing a similar level of oil consumption. Rebuilt the whole thing several times with new liners, new rings and new stem seals. Each time it was OK for a few hundred miles then returned to oil burning. Drove me mad. In the end in my case it was piston wear, just 0.05mm beyond spec. The pistons were able to rock slightly in the bores, wiping out the crosshatch pattern, glazing a band up each side of the liner. Every time I rebuilt it, the pistons trashed it again. In your case it's probably a different root cause but the interesting things were that it showed no symptoms whatsoever, no smoke or smells, even when burning 1.6 litres per 1000 miles, and compression and leak down tests were essentially perfect every time. There's a big difference between a gas tight ring seal and correct oil control. The leak down test will only tell you whether you have a good gas seal, so will show up bore scoring for example but won't necessarily pick up glazing. A good borescope and somebody who knew what they were looking for would have picked it up, but a cheap Android endoscope and my inexperienced eye couldn't make out very much. The glazing was clear though when I pulled the head. Mirror polished shiny silver patches on the left and right sides of all cylinders. By the time I found and fixed mine (new pistons) I also solved the mystery of why it didn't smoke ... the cat was burning up the incompletely burned oil and paid the ultimate price. Large chunks of the matrix burned away and collapsed! Link to comment Share on other sites More sharing options...
revilla Posted November 16, 2018 Share Posted November 16, 2018 Haha Ian only just saw your post after mine, you know what they say ... Speak of the Revill ... Link to comment Share on other sites More sharing options...
7 wonders of the world Posted November 16, 2018 Share Posted November 16, 2018 Re Bedding in:Bedding in gently as you did, may appear to be the best and kindest thing to do to a new engine, is, the best way to polish a bore, they should be bedded in hard for at least a dozen full throttle full rpm bursts lifting and coasting between each run, this should be done on initial start up of first thing on the rollers, after that driven hard with mixed loads and rpm, the engine should be run on something like millers for the first 500 miles.Baroscope possible followed by a full strip down is looking probable Link to comment Share on other sites More sharing options...
Graham King Posted November 16, 2018 Author Share Posted November 16, 2018 Thanks for all the responses folks, I know my local garage have a borescope so will ask them to have a look and see if they can help in any way. I’ll post back when I know what has been found but it seems likely it’s going to end up with taking the head off at least . All so frustrating because it all runs so well, but I can’t live with the oil consumption any more. Many Thanks.Graham Link to comment Share on other sites More sharing options...
oilyhands Posted November 17, 2018 Share Posted November 17, 2018 In my experience rebuilders do not always condition/de glaze the bores before fitting new pistons or rings, that is a surefire way to mess up the bedding of the rings. Bolt and braces approach says n ew liners, new rings and new stem seals as the current OE seals are not of sufficient quality and they may have been used on your refresh.Oily Link to comment Share on other sites More sharing options...
Leadership Team SLR No.77 Posted November 20, 2018 Leadership Team Share Posted November 20, 2018 "In my experience rebuilders do not always condition/de glaze the bores before fitting new pistons or rings"Surely not !!! That was one of the first things I learnt rebuilding Mini engines many many years ago, surely it's an absolute basic principle if you expect to bed new rings into an old (glazed) bore? For the work involved it's a fraction of the total work being done. Link to comment Share on other sites More sharing options...
oilyhands Posted November 20, 2018 Share Posted November 20, 2018 Couldn’t agree more, but I have seen 4 engines here with new pistons and old bores, seems crazy to me but there it is.Oily Link to comment Share on other sites More sharing options...
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