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molemot

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Everything posted by molemot

  1. Yes, isn't it? Anybody else wants to have a go at DIY turbo rebuilds, Jim and Gerry at www.gpopshop.com can sell you the bits and give advice by return of email. Not a difficult job for a competent spannerperson, the only special tool is a very fine pair of circlip pliers, I modified a spare set of ends to reduce their diameter and add an indentation to hold the circlip - then it's a doddle. LOTS of cleaning and general crud removal inside and out and a VERY clean workplace and latex gloves (OOOOH, Doctor) are a good idea. Torquing up the bolts which hold the turbine and compressor housing ain't easy as sockets and torque wrenches won't fit; but a spanner of known length, a spring balance (left over from setting the differential preload!) and some arithmetic works well. When fitting the turbo back onto the car, you will find out if you've got all the bits aligned accurately - a slight rotational error on the turbine housing makes the oil drain pipe the very devil to fit, now it's got a new full thickness not squashed gasket. The side of the flange only just clears the head of one of the bolts. I have retained the restrictor in the oil supply that was part of another turbo set up, and gives me a measured 2 litres per minute oil flow - book value for this turbo is 1.7 litres. All is well so far, time will tell! Now to sort out the wastegate to get the boost back to the book figure, at present the wastegate opens at about 6 psi. As there is a threaded hole in the bottom of the wastegate under the spring, I intend to make up a suitable plate to fit under the bottom of the spring and add a bolt and a locknut to adjust the spring pressure and thus the max. boost. More fun in the workshop!!
  2. After an annoying wait whilst HMRC decided to charge me vat on the parts (and on the postage, which I thought was a bit thick) I have now rebuilt and refitted the turbo. All is now well, the beastie howls once more, haven't yet exceeded 130 but it's had a number of max power/rpm in lower gears and absolutely no visible stuff comes out. Interestingly, very careful measurement of the original parts showed everything was still within limits, which is puzzling - but there's no argument with the results. There is significantly less sideways play in the bearings and the boost seems to build faster than before, but this is subjective only. All in all, a good result for about
  3. You could try using reed switches and magnets mounted on the gearbox; I would think this would be better than trying to mount stuff around the gear shift lever. I think simple solutions are best, so I would try to avoid software based interface cleverness if possible!
  4. Wayne - I agree that the turbine oil seal and probably the bearing,too, have most likely perished. As for the quality of the previous turbo rebuild, I can't say; all I did was bolt on a nice shiny turbo from an apparently reputable source. I think the long periods of inactivity probably has some bearing on the premature failure. This time around I'm doing my own rebuild, so I'll know what state the innards are in. I did find it interesting that the ex-Mini turbo has effectively got a restrictor built in, which my tests show would give close to the book flow rate. One must remember that the oil isn't just for lubrication, but for cooling as well - this turbo has no water cooling and the oil flowing through it serves to carry the heat away to the oil cooler. Today I'll strip down the ex-Mini unit, another interesting learning process! "An engineer is a man who can do for five bob what any bloody fool can do for a quid!"
  5. Now,that was a very entertaining day! After running the engine with just the manifold - and no smoke whatsoever - I put the turbo back on. Started up, and the smoke was back again. Fairly conclusively a turbo problem. Whilst waiting for my brother - who was to be my assistant in the flow tests - I remembered I had a spare turbo under the bench in the shed. Although this had been removed from a Mini (and recovered from a skip, but that's another story) it's still a Garrett T3 unit, so has a common centre section or CHRA. A useful thing to dismantle before the real thing. The oil supply to this turbo passes through a banjo bolt, the inside diameter of which measured 5.7mm - compared to 7.25mm for the same turbo on the Lotus. Now to the flow tests. Having run the engine until the fans cycled, I disconnected the oil drain pipe and arranged a suitable receptacle. The engine was then restarted, rpm set at 3000 giving an oil pressure abve 50psi, and stopped once the receptacle was nearly full. This was measured at 0.85 litres in 16 seconds. This equates to 3.19 litres per minute passing through the turbo; nearly twice the Garrett recommended figure of 1.7 litres per minut. If you apply these results to the Mini orifice diameter of 5.7mm, this would flow 1.97 litres per minute, much closer to the book figure, and an interesting confirmation of the experimentel results. The final stage of the experiment was to modify the Mini banjo bolt to be a restrictor in the oil inlet of the Lotus turbo- as it had come from a T3 turbo, no damage could result. This was duly done, and the engine run once more. I wish I could report that all the oil smoke had gone, but life and mechanicking isn't like that. There's still significant smoking, so tomorrow the turbo comes off AGAIN to be stripped down ready for the arrival of the overhaul kit. Meanwhile, I may be able to substitute the CHRA from the Mini turbo for the Lotus one, if the turbine and compressor are compatible.
  6. Jens - I bet you're right in most cases - but I've never done that; I always modulate my driving so that the last few miles are gentle - usually in traffic, anyway, getting home - and always allow a couple of minutes at idle before shutting down. One of the reasons I want to dismantle the turbo myself is to SEE what, if anything, has failed. There's no sign of coking or any deposits inside the turbo oil drain port or the first few inches of the drain pipe. I'm going to take this off for a proper inspection next. Blowing through the oil drain just produces a breeze from the crankcase breather, whether at low pressure or 140 psi from my airline. No backpressure in either case. Exactly the same resuts from blowing the other way. Once Ive got the flow figures from my tests, I guess I'll dump the whole turbo in my cleaning bath until the parts arrive. Might help towards undoing all the nasty rusty bolts!
  7. Jens - I refer to my previous posts. The turbo probably didn't need any restriction in its oil flow BEFORE I changed the oil line for a non-Lotus part. Now? I don't know - thus I'm measuring it to find out. Pressure is different from flow rate, pressure in a fluid is constant so that's not a worry. As long as it flows ENOUGH oil , of course. I know the pipe flows far too much, but once the line is fitted to the turbo with the turbo bearings restricting the flow, at this time I have no data. Hence the tests. As far as rebalancing is concerned, the rotating assembly is a balanced unit anyway and as long as nothings broken off it, it should still be balanced. We shall see! I intend to refit the turbo and measure the oil flow THROUGH the unit - once I've got some concrete data I shall be able to make an informed decision. At least I've got a plan!! If the turbo has failed, SOMETHING has caused it. It has only done about 8000 miles since I bought it as a reconditioned unit in 1992, so it has done little work. My thoughts are internal corrosion due to lack of use - but the problem has only arisen within 120 miles of fitting this new oil line, so I want to eliminate the possibility of oversupply of oil before I go any further. The car has had regular oil and filter changes, runs on synthetic oil, and only rarely uses max power - most of the usual turbo failure causes should be able to be eliminated. I'm mechanically sympathetic - as you are when you've built it yourself! - and I don't want to blindly fit a shiny new turbo without finding out what has caused this one to fail - if indeed it has.
  8. Further to previous posts.. Have discovered an American firm called G-POP SHOP who sell rebuild kits for turbochargers. The G3 Garrett is $78 plus $25 insured airmail. Thats about
  9. Thanks, Jens - I tend to agree it's the turbo, but Ill play with it a bit first. The rebuild kit sounds interesting, I'll be able to find the failure mechanism and see exactly what's gone wrong. I'm also a pigheaded chap who likes to do EVERYTHING himself; having rebuilt this beast from stem to stern over the years - including bodywork and paintspraying - I'm not going to let a turbo put me off! The chance of it actually failing catastrophically in service is slim enough for me to discount it. Anyway, there's a strainer in the sump for the big bits and a filter for smaller lumps!! Also, if my theory about the wrong diameter oil line is correct, a new turbo will just go the same way as the last. If there's too much oil being supplied, changing the turbo won't cure it. Measuring the oil flow rate is the only way to find that out - and it's free!
  10. Paul - I am intrigued that you think 130 psi is worryingly low. The car has had regular compression tests over the 17 years that I've owned it and has always returned a figure of 130 to 135 psi with no smoke or other problems. The book says 130 psi; I don't think even Lotus would quote an inaccurate or worryingly low figure in their servicing notes. See my previous post for details of the Ultimate Test! I've found a Garrett T3 rebuild kit on Ebay for $99.95, the turbine and compressor being OK and a pre-balanced unit, changing the bearings and seals would probably suffice. I've spent a lifetime unpicking engines of all sorts from highly modified to mundane, including aircraft engines, so I've done a few compression tests too - but definitely not as many as hot dinners!! Or even bottles of wine...
  11. Further to previous posts - In pursuit of a definite answer to whether this is a turbo or engine problem, yesterday I did the Ultimat Test. I blanked off the turbo oil line and ran the engine bereft of turbo ( and also exhaust pipes and silencer!). It wasn't as loud as I had feared, and ran up to operating temperature nicely. Nothing - absolutely NOTHING - visible issued forth from the exhaust manifold - except for a few flames when the engine was revved. I revved it a few times and held the rpm at 3500 for a few seconds and nothing of any consequence came out of the manifold. This, to me, proves the gas generating side of the equation is not the problem - I never thought it was, but it's nice to get proof! Next ploy is to reassemble the turbo, run the engine until hot,detach the turbo drain line from the sump, and measure the oil flow rate through the turbo. That should give some concrete data to work with. At present, the 7.25mm hole in the turbo oil inlet flows about 2 litres in 20 seconds, rather more then the 1.7 litres per minute the turbo requires according to the data I have. Thats about 3 times too much; flow rate is proportional to the area of the orifice, so the sums show a 4mm hole would flow about 1.8 litres per minute which seems to be OK and also "feels" right. So if the flow tests prove the 2litres in 20 sec. figure, I'll make up a 4mm restrictor plate and do the tests again - if this gives the right figure, it's road test time! Turbo may be lunched already, turbine play is excessive, so playing about with it isn't going to matter.
  12. Paul - your reference to compression pressures - on a non HC engine the book figure is 130 psi.
  13. Midnight research on the interweb has, I think, yielded the answer.....It's a self inflicted wound. When I put the engine back in in August, I finally decided to change the nasty rough spiky rip-your -hand open oil line to the turbo, with a lovely shiny new Goodridge hose. I t looks very pretty. However, it lacks the 90 deg.piece of metal pipe which, on the old one, lead to the turbo. This, I now feel, was a deliberate restriction in the flow to prevent the turbo from being inundated with oil - exactly the symptoms I experienced. Of course, I've thrown the old one away in a fit of tidy tidy (VERY unusual for me!!) Tests show that the new oil line flows about 2 litres in 10 seconds - rather too much I thought at the time, but still didn't twig. So the problem seems to be too much oil, not restrictions in the drain tube. Same thing, different reasons! The clue came from the website of the Turbo Clinic up in South Wirral - thank you, gentlemen! Still not proven, of course, but it is a definite probable cause. Thanks for the replies, chaps - and don't any of you change that ****ing hose for anything other than the proper part!!! Best regards - JD Thinks - Will the turbo have survived? Turbo seals are labyrinth or like piston rings - maybe I'll be lucky, but I'm not holding my breath!!!
  14. There's no great oil slick in the inlet hose, and with the cranckcase breather hose detached no noticeable fumes issue forth when the engine is revved. This, plus the good compression readings, makes me think there is no problem with the piston/rings/liners. I can't believe I have a valve guide problem. It may be that I have an obstruction in the turbo drain pipe, that comes off tomorrow after this night shift at Terminal 4 Heathrow. But its a bloody great tunnel of a thing and I hold up little hope of a significant blockage. Oh, but I hope there is.....!
  15. Here we are again, minus a few bits of skin and blood, bruised knees and cut scalp, usual stuff from climbing in with the engine. Turbo is now on bench. Some oil in compressor side - but that's where the cranckcase breather goes, so inconclusive. The turbine has sideways movement of 25 to 30 thou - about.63 to .75 mm. A bit large, methinks, but not a shagged out rattling mess. Then again, it only really lets rip under extreme provocation. Other than the turbo, the only real way to get that much oil into the exhaust would be down a valve guide, and that would be progressive wear not sudden onset failiure. Must Google some more Info!! See next enthralling episode.....
  16. Cheers for that, Jens; was going to be my next step - got too lste last night! My previous turbo was still boosting ok minus lots of bits of compressor and significant shaft wobble. This one has spent a long - like 5 years! - time idle, corroding internally I should think. All the engine internals are perfect, I only saw them a month or so ago when I stripped it down chasing a rattle which turned out to be a leaking no.4 exhaust gasket! Anyway, off to the workshop now and I'll have a shufti at the turbo input. Best regards -- JD
  17. Well, it was a nice sunny day, so I unwrapped the beast and got it out of it's lair at the bottom of the garden. Off we went in search of illegality; found a traffic jam. Half an hour and about 3 miles later, things cleared on a dual carriageway - all except for the standard issue WHITE VAN!! Finally I bullied him out of the way and applied full power in second gear. He just disappeared! Not receding into the distance in the mirror, but behind a giant smoke cloud, the like of which I hadn't seen since my supercharged MG TC decided to flow too much oil to its Shorrock back in 1971. Cloud wasn't thick enough to cause an accident, but jolly impressive nonetheless. Back in the workshop, all 4 compressions were 135 psi, disconnecting the turbo from the plenum didn't stop the smoke shorting out one plug at a time also had no effect. So; compressions OK = rings OK; it doesn't seem to be one cylinder and ALL the guides won't fail at once; prime suspect is the TURBO, possibly a duff seal between shaft and turbine wheel, dumping oil into the exhaust. Anybody got any other ideas?
  18. It'll probably turn out to be a crap earth somewhere.... voltmeter should read battery voltage and not zero when ignition is on, so there's some intermittent connection in the circuit I should think. Try testing through with a voltmeter and wiggling things about!
  19. I had the same problem and replaced the 1st/2nd synchro when I had to rebuild the gearbox following crownwheel/pinion failiure. The pinion being also the gearbox mainshaft meant it all had to come apart! New synchro cured the problem completely. As a matter of interest, the crownwheel/pinion alignment is set by a thrust washer in the gear cluster; all CWP sets come with the required pinion projection engraved on them. Lots of interesting measuring! When I ordered the correct thickness of washer, I was told that although "they" sold quite a few CWP sets, nobody had ever ordered a thrust washer before - so there must be a few cars out there with improperly adjusted CWP sets!
  20. On the subject of driving cars bereft of MOT; you are allowed to drive it to an MOT testing station for a pre-booked test. Thus phone your MOT station, ask them to put you in the book in case the pointy head brigade query it - but tell them you may well not appear - then off you go, quite legally. Ideally in the direction of the MOT station. If it's a car you're contemplating buying, an MOT test could be a good idea anyway, at least you'll get a list of Things to Do.
  21. Check the correct ride height - 170mm to the point where the lower rear link joins the chassis. I've just fitted new dampers with adjustable rear spring platforms; I initially set the platform to the same height above the lower spindle as the original. Now I've lowered it about 2cm the ride height is correct! Only done about 60 miles so far so will keep an eye on it "settling" further.
  22. Don't confuse wastegate with dump valve. Wastegate discharges exhaust from turbine input through the silencer; dump valve dumps excess boost input from plenum chamber on overrun. Max boost should be about 7 to 9 psi; if much higer than this, the wastegate is U/S - probably a holed diaphragm. These are obtainable - at a price(!) - and require the wastegate to be removed and dismantled to change. Broken studs. drilling. tapping...all that good stuff. The nice waffly sound from the overrrun comes from the plenum chamber dump valve which is the silver thingy mounted at the rear of the plenum near the fuel pressure regulator.
  23. If you mean the small panel on the centre console, First remove the knobs. they are held either by grub screws or else there is a spring loaded plunger which you depress through a small hole in the knob. Once the knobs are off, there are two screw hidden behind the heater and A/C knobs; remove them and the panel comes off. You will need to remove the radio to get access behind the panel. There are three bulbs, held by plastic, click-in-place fittings accessible once the radio is removed. I was doing this yesterday!
  24. Hi troops...to disable the intermittent wiper unit, unplug the two connectors to it - one male and one female - then plug them together!
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