SundanceGarage

Hey everyone,

Been a constant lurker in the background of these forums but finally created an account to make a post in search of some advice for some issues I've been having.

Some important things to note:
The car was built to 3.6L spec with LN engineering "Nickies," Mahle pistons, LN thermostat, water pump and other components that I believe were sourced from LN.
The shop that did the rebuild was performed by Autohaus in Peapack, New Jersey
The rebuild was done around 48k miles, car now has approx 110k miles.
Rebuild was done prior to my purchase, 3 years 27k miles since purchased.
Was diagnosed with bore scoring prior to the rebuild

I'll try to provide as much detail as possible while still being concise.

Roughly one year after purchase I noticed a decent amount of oil consumption. Roughly 1qt per 1.5 gas tanks. I was also getting smoke on start up and occasionally on rev match down shifts or revving the engine. A local shop, R&D Automotive (Albany, NY), performed an oil change and inspection and said the rear main seal was most likely starting to go bad, no confirmation though. They said not to worry and to consider at at some point in the future.

Little by little I noticed the consumption issue getting worse and brought it back to R&D. They were to perform the 100k mile service and inspect the RMS again. At this point they said the RMS was fine but the Air Oil Separator was going bad. I decided to take the car back and replace the AOS myself.

I replaced the AOS with an aftermarket kit from FCP euro and the consumption issue seemed to go away, temporarily. After about 2 months I noticed the same symptoms, smoke on start up, similar if not higher oil consumption and an occasional smoke screen out of the exhaust when rev matching downshifts or revving the engine with the clutch engaged.

FCP sent me a new AOS which was a Porsche genuine unit and I installed that along with all new vacuum hoses to the AOS.

In replacing the vacuum hoses, I didn't reinstall the boots on the intake manifold properly and there was a noticeable vacuum leak, check engine light and other issues. I fixed the vacuum leak but the CEL still remained. The code was a misfire on cylinder 2. The spark plugs appeared as if they had never been changed so I replaced all of the spark plugs and the code went away and the car seemed back to normal. Other than a lot of smoke on first start up, which I attributed to excess oil from the AOS and other issues needing to be cleared out.

Test driving the car, things were operating as normal and I thought the issue was resolved. The next day, I started the car up, more smoke on start up which I figured would linger for a little while. I took it out for another test drive and after 5 minutes I was getting the same issue with smoke from the exhaust when downshifting. Then, when I revved the engine, there was a loud bang and the car shut off, not small pops out of the exhaust which would sometimes occur, if it was running rich. I was close to home so I coasted down my street. I tried restarting and got another check engine light. Similar misfire on cylinder 2.

At this point I replaced the coil packs, which appeared old but not in horrible shape, as well as another new set of spark plugs and noticed that there was another vacuum leak from the intake manifold, which I think either caused or occurred when the engine shut off. I fixed both and the car seemed okay but was still getting a lot of smoke and oil consumption. I took it for one drive for about 25 miles and it consumed about 1 quart in that range. Same symptoms as before and shortly after the check engine light came back on, now there are misfires on cylinders 1 and 2.

The 2nd set of spark plugs is also noticeably coated in carbon deposits/oil after only being in the car for a couple of days and only used in start ups and the drives mentioned here.

I've since sent in an oil analysis to Blackstone laboratories and am waiting on a result. I think the next step is a compression test.

I have not replaced the fuel injectors. I was able to test the fuel pump and that is working properly. At this point, after replacing the AOS twice, spark plugs and coils, I am not sure what could be causing these issues. Especially given the huge amount of oil consumption and the bizarre consumption with clutch engagement.

Any help or ideas you all have would be greatly appreciated! There is a part of me that wonders if I have been just overfilling and the engine has been burning off excess as the car seemed completely fine before changing the AOS and still isn't making any weird noises throughout the rev range. I was under the impression that I shouldn't have issues with bore scoring after these modifications but I am sure there could be other things that could cause these issues.

oldbutslow

A quart in 25 miles!! If I knew who the God of Piston Rings was, I’d give you his name. I don’t mean to be snarky, but you’d be best talking to L&N. Best of luck with your situation, BK

SundanceGarage

Ha, that's what I was thinking! As for contacting L&N, I had a phone call with them about a week ago and they suggested sending a detailed email which I did and am waiting on their response. Sent them most of the same info that's in this post. Just hoping for any ideas as I've tried to do plenty of searches but can't find much.

harveyf

Thanks for the complete concise writeup. Just for the record, add the year of your car. I am assuming it is 2006-08?
A couple of diagnostics that I would recommend.
1. Drain the oil completely and measure how much you got out. Compare that to the refill number w/o filter change shown in your Owners Manual. Of course, if you get significantly more than spec, that would point to an overfill and a faulty oil level sensor circuit.
2. Search for Callas Manometer on youtube. Check your crankcase pressure and evaluate versus what he says in the video. BTW, it is OK to purchase the $42 manometer from Amazon, although you will also need to buy a new oil filler cap, so you can modify your old one to have the nipple fitting for the manometer.

3. It sounds like you are a motivated DIY guy. If you haven't already, get a Durametric so you can be checking your data as you go.

BTW in my experience "really bad rings" would indicate as a constant cloud of smoke. Smoke on downshift- when you are in "overun" there is a negative pressure in the cylinders. Classically on an "upright" engine, this can pull oil in through worn valve stems. I guess on a flat 6, it could pull oil in through the rings. Not sure. My first car burned a quart of oil in 50 miles. There was a very obvious cloud of smoke that followed me around everywhere!

If you get the manometer set up, you can disconnect the AOS tubes at the intake manifold, in which case your crankcase pressure should be a modest positive value. If the rings are really bad, you'll start to get elevated postive numbers. I think Tony goes into this.

SundanceGarage

Thanks for the thoughts, I appreciate it!

Car is a 2006. Don't know how I missed that in the original post.

I did drain the oil and only got 5.5 quarts out of it so about 2 quarts short. I also refilled to 7.5 qts and am getting 3 out of 4 bars filled on the electronic oil measurement so I can confirm I haven't been overfilling.

I also did a compression test and compression was about 100psi lower on cylinder 1 than the rest of them. So all signs are pointing to repairs beyond my capabilities.

Had a great conversation with Brandon over at Slakker and I'm leaning toward sending it there for a rebuild.

harveyf

Yeah, that low compression will most likely be your problem.
Brandon can fix you up.