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Smoking is that Bad? Yeh Sure, Help..

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J

Jim Weatherford

Jedi Trainee
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BAD NEWS: I was getting Black Beauty, Jensen Healey #13046 prepped and ready for my first foreiy into SOLO II. I was out at The Streets of Willow shaking her down and was running very well on an Open Track Event and giving a few Miatas a rear view of the Jensen Healey when something broke.

I'm still trying to figure out exactly what it was/is that happened. Smoke started billowing out he tail pipe and looked like oil smoke but it just didn't have an oil smell, or water or anti-freeze or... I pulled the plugs and the plugs had oil on them and the top of the pistons were a wash with oil, especially #3 & #4 cylinders. I used a lighted bore scope and there was no doubt of the oil. I suspect hydro locking, but I need to know more.

I put her back on the trailer and took he to the shop where my mechanic did a leak down test which was pretty good and yet I had lost serious oil pressure at idle, so it looks like a total rebuild at this point, I know I didn't over rev her, (6K RPM's Max) but something happened. I now have three (not running) 907 engines so, it looks like I'm going to get a chance to rebuild the engine to a 2.2 configuration, wheather I like it or not.

If you have any idea what may have happened in the above failure mode, please let me know. Buy the way the engine continues to run fine (Just smokes like it on fire!) and above 1,000 RPM's I have normal 50+ PSI oil pressure. It doesn't seem to be valve guides, though that was my first thought as that is a known failure mode.

Any ideas and assistance would be appreciated. Thanks.
 
Sounds like a damaged ring or piston.
The low oil pressure at idle may just be the affect of track-driving. My car has excellent oil pressure when street-driven, but it gets much lower at the track.

I pulled this piston out of my Spridget after racing at Summit Point last Fall. The car ran pretty good, but had one partly-fouled plug and plenty of smoke. The upper ring land failed and pieces of the ring were banging around into the piston (the broken ring pieces caused the rectangular marks in the top of the piston).

1500_piston.jpg
 
Yes Sir, I've seen that before, it could be a few things but the bore scope didn't show and signs of damage on the piston tops.. I'm going to check my vent & breather hoses, I may be forcing oil through the carbs or some other equally weird thing, I just replaced a bunch of them, I may have screwed something up myself. I have 135 lbs of pressure and almost "0" oil pressure at idle. It runs very well, just smokes awfully.

Thanks for the photos, they really show a story.
 
I think last evening the problem has been identified... We suspect it over presserization of the crankcase, the solution may be as simple as checking the crankcase vent hose, but seldom is it that easy, I also have been blowing oil up through the rings too. So while it sounds like a simple fix, in all likelyhood it isn't unless I'm very lucky.

I have two non-running spare engines (all '73 907's) I think I'm going to rebuild one to the 2.2 litre version. This way I'll have a good one when I'm done. Any thoughts and Ideas.
 
Jim, a non-functional crankcase vent system will cause oil to blow by the rings, and also be sucked through the carbs. I think you are on to something pursuing that avenue.
Jeff
 
Thanks, That is the direction I'm going towards... first.
 
would it be possibe to blow a head gasket in such a way, piston chamber to oil return? and with an over pressured crank case to cause smoke like that?? just curious.



mark
 
Mark, if the head gasket let go like that, all the plugs wouldn't be affected. From what Jim says, or at least my interpretation of it, all the plugs and pistons were oily.
Jeff
 
The 907, if memory serves, has free standing wet liners, like an Alfa or Jag V-12, and a blown or weeping head gasket would likely blow coolant out before it would pressurize the crankcase.

Jim, did you really mean that you have 135 pounds of oil pressure? I would think that was a bit excessive myself.

The 907 lower end is one of the stoutest designs I have ever seen, with connecting rods that would embarrass a big block V-8. The weakest part is the head gasket area, particularly the perimeter around the water jacket. Never clean that area with any sort of powered buffer. A single edge razor blade held perpindicular and a scraping action will take you down to the original machined surface and no further. The aluminum will be all sorts of ugly colors, but don't be tempted to "shine 'er up," or you could have heck keeping the coolant or oil (especially at 135 psi!) from seeping out.

Regards from the Lone Star State,
Steven
 
Steve;

I'm not surprised at your suprise! If I mis-spoke, Ignorance on my end rules. What I meant to say was... 135 Pounds compression per cyl., also the leak down test was good also.

I purchased a second engine in very good condition yesterday and I'm going to install it then work out the kinks in my origional, I'll know for sure when I tear it down at to the actual problem. Many thanks for the info.
 
I was able to find a replacement engine on the JHPS web site, it was a great find at minimal dollars and the PO even gave me the engine stand in the bargain.

Anytime you can find a complete, functional Lotus 907 engine with 41,000 miles on it for $450.00 USD that is a bargain. The PO had swapped it out when he put a 2.2 Liter 907 in his JH.

This will allow me a chance to rebuild the engine out of #13046 and stay on the road all at the same time.
 
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