Laust's Jalpa Project


Page 5 - First teardown and re-installation (Jan-Feb 2006)



While the Jalpa worked quite well for the past 500 miles, I was not satisfied and here is the list of problems and activity goals justifying this tear-down:

1. Car could barely build 5 psi boost pressure and the exhaust switching was stuck.
2. Too much noise in differential (chickened out during last attempt of correcting it). 
3. Much too much oil in intake tract and even in manifold. 
4. Cylinder heads with unknown torque and probably too little for a boosted engine. 
5. Knocking sound when cold. 
6. Cam chain tensioner functionality was not fully known to me and therefore chains may not be properly tensioned. 
7. Intake manifold was leaking slightly at O-ring joints to cylinder heads. 
8. Always worth to take a 2nd and 3rd look at how to lower the engine compartment temperature. 
9. Look for better way of disconnecting the (very difficult to get to) lines to the electric oil pump. 
10. Modify if necessary the somewhat complex AN connection to oil filter housing to minimize potential for oil leak. 
11. Modify cooling system to automatically evacuate air pockets (which caused one overheating incident). 
12. Rebuild clutch slave cylinder since it was very difficult to build up pressure at last engine installation. 
13. Have the cam covers and intercooler powder coated (instead of being painted). 
14. Make yet another attempt to solve A/C leakage problem and inaccessible filler and purge ports. 
15. Try to eliminate fuel smell. 
16. Too many external oil leaks.

P2190043.JPG (193388 bytes)
P2190043 (2-19-2006): I was convinced that the lack of boost was caused by a damaged turbocharger turbine wheel from a loose cleaning pellet which were used in preparation for the ceramic coating of the headers. So I went on eBay and looked for turbocharger substitutes. As it turns out, there are some absolutely ridiculous sellers there and while I was reporting product misrepresentation, another very good deal came up, namely $150 for a set with brand new turbine housing (with built in wastegate). The other "deal" went through also, so I ended up with two sets (4 turbos). Additionally, I bought some service parts (seals, bearings, clipped wheels) and expect to have one rebuilt set ready as back-up and another for sale on eBay. My turbos did not have any damage, but one had excessive play, just beginning to touch the housing, so I swapped the center section with the best of the other four available.

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P2030017 (2-3-2006): This is where the lack of boost was to be found. My exhaust air valve had seized open as seen in the upper part of the picture, essentially as a result of bad material choices (stainless shaft, oil filled bronze bushings and aluminum housing with thermal coating on exposed parts). After some high temperature material friction testing I then spent a lot of time manufacturing the stainless steel exhaust air valve (seen in the front) with mild steel bushings (no lubrication). The actuation mechanism was also modified to fit the expected actuator location.

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PC310738 (12-31-2005): This is a look into the intake manifold where large puddles of oil can be seen. The only oil sources possible were leaking turbo(s) and/or an inadequate air/oil separation in the Positive Crankcase Ventilation (PCV) system, which bleeds into the intake tube of one of the turbos. After evaluating the turbos, it was very unlikely, that they were the source.

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P1110746 (1-11-2006): This shows the outlet(s) of the PCV system and the two cylinder heads are connected via a large hose connected to the fitting seen to the upper right. I initially used the upper small hole, but then realized that Lamborghini had a very good air/oil separation design just underneath in the large (normally capped) hole. The "hamster treadmill" is mounted with the thick screw (both seen sitting on top of the cylinder head) at the end of the camshaft, essentially acting as an oil centrifuge creating a small center chamber where oil is almost absent. So a fitting extending into this chamber was installed in the cover plate and the other end connected to the hose shown leading to the intake pipe.

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P2190044 (2-19-2006): The manual says: "The nuts 8201101 11 that fix the cornet heads must be tightened with dynamometric key at 7 kgm. (fixtures: keys set 9007091)". That translation (from Italian) I re-translated to mean: "torque the cylinder head nuts to 51 ft-lb with the best means available". So I bought a 6-point 17 mm standard short socket (3/8" drive) and machined it as shown (smaller diameter, two flats and a chamfer on top) to make it slip past the camshafts. The final dimensions of the socket are 25.4 high, 23.0 mm OD, 21.5 mm between flats and a 2.5 mm 45 deg chamfer on top (just in case others want to copy this). Since the combustion chambers and head gasket now are supposed to hold boosted combustion pressures (14.5 psi max), I found it prudent to increase the torque. In the proper sequence each of the head nuts and studs were oiled and the tightened to a torque of 75 ft-lb. The studs and nuts has a relatively fine thread so this will translate into a significant clamping force. All the torquing sequences felt right (gradually increasing torque).

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P1080744 (1-9-2006): In the process of searching for the knocking noise I discovered that the one of the chains were slapping a bit on its guide making a knocking noise, so I set out to learn the intricacies of the chain tensioners, by dismounting one. As could have been expected with a little more foresight, a cam turned on its own scrambling my cam timing. The spring loaded idler wheel on the cam tensioner can be fixed in two ways, which can be a little confusing. At the same time the spring tension is inadequate to overcome the force of the cam twist at the cam position suggested in the manual. I made a worksheet and found that the cams are in a "safe" position (two cams opening and none closing) if the crank is at 620 degrees (clockwise from front) relative to combustion TDC of cylinder #1 for rear bank and at 260 degrees (same reference) for front bank. At those positions untighten (less than 1-turn) the side screw on the tensioner and screw in the threaded rod in with a screwdriver until a significant resistance is encountered (chain over-tight) and then back off by 1/4 turn. Lastly secure the rod with its counter nut and cover and tighten the side screw. The side-screw is really only for fixing the (rotational) orientation of the idler sprocket and for transportation of (all the parts of) the tensioner assembly.

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P1070743 (1-7-2006): I was also looking for the knocking at the connecting rods, but found all (sort of) OK there. The picture shows the worst of the bearings with some debris embedded and a scratch. The camera flash shows it worse that it appeared in reality. I left the bearings as is, but will replace them "next time" since the bearings are available through GTCP at a reasonable cost.

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P1170005 (1-17-2006): The intake manifold took so long time to fabricate, that I completely forgot that the dimensions of the runners were selected based on pipe availability and therefore had slightly larger ID, than the mating runners in the cylinder heads, hence the difficulty in sealing. So, as initially intended, I made some conical inserts to smoothen out the transition, glued them in with J&B Weld and planed the mating surface. This now appears to work well.

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P2080029 (2-8-2006): In addition to all the thermal coating I also added an adhesively backed heat barrier (2000F rating) to the thermal SS shield underneath the intercooler. I know greasy fingers on the pretty exhaust, but that should burn off. I reintroduced the molding between the edge of the cam covers and engine compartment walls to minimize conductive heat from the headers, but with limited success since there still is a sizeable gap there.

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P2100032 (2-10-2006): These are the two lines to and from the electric oil pump, which is so well hidden behind the gas filler neck, that undoing the hoses from the pump is virtually impossible without removing the filler neck. So I got a couple of 90 degree AN-6 and AN-10 joints, essentially a $100 convenience modification, ouch.

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P2190045 (2-19-2006): It turned out that the location of the electric water pump makes it an excellent trap for air pockets, since it is unable to create any negative pressure to suck up coolant, when spinning in air. This caused several difficult evacuations and one overheating incidences. My solution was to mount a nipple high on the scroll and (indirectly) bleed it back to the expansion tank.

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PC300735 (12-30-2005): Additionally I found a bleed screw for the radiator up front, which does not show up in any documentation. The screw (with an inside tube to the top) is located at the bottom of the right radiator tank.

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P2020016 (2-2-2006): This is the clutch slave cylinder with the piston on top showing the new and old seals. While not worn the old seal clearly has lost all its tension to maintain a safe sealing contour. The cylinder and piston were not scratched and not worn at all. The seal was a pain to get on the piston though.

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P2040019 (2-4-2006): This is the process for adjusting the differential crown wheel position (.006" closer to the pinion). The hubs are turned down a bit on the outside, a sleeve is pressed on, the assembly is mounted in a lathe with the desired eccentricity and the sleeve (on the hub) is turned down to the desired OD. This picture is of the process of making the eccentric set-up. For those measurements I had to make a temporary inner race for the (very large) roller bearing.

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P2040020 (2-4-2006): Here the sleeve is turned down to the appropriate OD (4.330" +- .0005"). I could probably have pushed the crown wheel .004" to .006" further in, but it is certainly better to have a little noise left, than no differential at all. After a few miles of driving it appears that the noise has been (significantly) reduced to an acceptable level, even with a thinner oil than Red-Line's Heavy Shockproof, which I previously used.

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P2190041 (2-19-2006): I milled the powder coating off the logo on the cam covers. Picture taken with cam covers installed, so the covers are already dirty.

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P2190046 (2-19-2006): Although I have only once used my A/C (to see if it worked) and very often drive with the top off, I think "if it is there, it should work". So I once again aluminum brazed a tubing and managed to relocate the inaccessible filler and evacuation ports on the compressor as the picture shows. It is getting very crowded. Hopefully it works this time.

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P2190042 (2-19-2006): During the conversion I reverted to the European version of the gas tank venting, which, through loops near the rear window, vents just in front of the rear wheels. However the gas smell was very noticeable especially when working under the car, so I decided to try to fit one (of the three!!) charcoal canisters again. Miraculously I found an almost ideal place for it as seen in the picture. The purging of the canister to the engine goes through a 1/32" restrictor and a check valve (no boost pressure to the canister) to the vacuum manifold, which can be seen in previous pictures.

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P2080026 (2-8-2006): In the search for (internal) oil leaks I mounted a couple of small "catch cans" as seen in the bottom middle of this picture. One collects oil, that may be pushed out of the oil sump through the drain pipe (unwanted back flow) and the other is from the air intake tube which has a small drain pipe if too much oil goes through the PCV system (into the air intake tube). The main external oil leak was through the oil sump gasket, which I renewed and sealed with "Yamabond". It appears that I stopped most of the oil leaks, but the engine is still not 100% leak free.

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P2050022 (2-5-2006): This is a picture of the heaviest loaded (most problematic) engine mount and as can be seen, the new ones I got from Raymond Stouffer ( held up well after about 500 miles. However the thick structural washer shown makes that possible by distributing the load over a larger surface.

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P2080030 (2-8-2006): Another very busy corner of the engine compartment. I managed to move the heat shield protecting the CV joint/boot from the other to this side.

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P2100031 (2-10-2006): The Jalpa is very thirsty. OK, maybe not that thirsty, since I had one gallon of motor oil and 1.5 qt of gear oil left over.

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P2140038 (2-14-2006): Here is my attempt to repair the right door catch, which was non-functional and had disintegrated parts. The large steel spacer is not shown here. The effort was only partially successful since the intermediate stops still do not function, but the all important final stop functions very well. The door catch bracket shown is a pain to get to and even worse to install. It requires very flexible arms and hands.

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P2180039 (2-18-2006): The largest weakness of the Jalpa is its body flex. The tunnel cover has more functions than just being a cover. It is made of 2 mm steel and has 34 + 8 mounting bolts (two separate covers) and also serves as a stiffening structure ... if properly mounted. In spite of this, the car could benefit from more rigidity.

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P2180039 (2-18-2006): And finally, I hope and it now appears, that the car will live up to its new badge.


Now it is time for some more engine management optimization, air fuel ratio and ignition timing optimization and some simple joy rides.

- Laust