Hi everybody
I've been lurking here for a couple of years and now I need your help. I also know that this isn't the right place to post this but for some reason I can't start threads in the other areas.

I need your advice on the rebuild I have done, I'll try to keep it as concise as possible...

TL;DR rebuilt myself. Drove in gently for ~600km, noticed high oil consumption. After that did some pulls and then it consumes 2-3 liters oil in 15 mins....Barely runs. What could be the cause and what to do?

Some info:

• RX8 from 2004, original 13B-MSP 6-port engine that has gone 110 000 km.
• Had hot start issues prior to rebuild (had an upgraded starter that helped a bit), otherwise it ran quite good (not producing the stated 230 hp though...)
• Completely new rotor housings.
• Lapped side-irons (did it myself with lots of advice and instructions from a pro, used silicon carbide 320 grit)
• Street ported irons by a pro.
• Rotary aviation Apex seals.
• Complete rebuild kit from atkins rotary (master kit, or whatever it's called)
• Increased oil pressure regulator kit from atkins (front and read, set to 105 psi)
• Thermal oil pellet without the spring in the front of the eccentric shaft.
• Oil jets in the eccentric shaft without the spring (the kit from atkins)
• Stronger stud kit from turbo source (those chrome-moly), and I increased the tightening torque as specified by turbosource
• New bearings everywhere except for the rotors.
• All tolerances checked during assembly, and we were reeeaaally thourough with everything. Used lots and lots of oil and vaseline.

I started it up and it ran just as it had before rebuild. Still had the hot start issue though ... but apart from that everything seemed ok.

Started the break-in with 5w40 fully synthetic oil, let it run for like half an hour on ~2.5k rpm, then changed oil. Drove 50 km at < 4k rpm then changed oil... gradually increased rpm to ~6k rpm the next 200 km, then oil change...

After that I drove 300 km very easy with varying rpm upwards of 8k rpm. I noticed an unusually high oil consumption, like 1 litre per 150 km (?). I topped it up regularly. I checked the plugs and cleaned them a couple of times. They had quite a bit of carbon build up but were "okay". Hot start issue persisted.

After ~600 km I changed oil again and took it out for a drive. Ended up with some sports cars and did 2 or 3 VOT to redline. Came home and it wouldn't run under 4k rpm, sounded like it was running on only 1 rotor.

I felt WTF, cleaned the plugs again, topped up the oil, took it out for a gentle drive around the neighborhood at 5k rpm for 15-20 min then the oil refill-light came up. Backed it in to the garage (still wouldn't run under 4k rpm), stepped out and my eyes burned from all the oil and/or gasoline in the air

It had consumed 2-3 litres of oil in 15-20 min...

What do you guys think? Oil scraper rings/seals broken? Is it just that the lapped irons haven't mated with the seals? Or is it the increased oil pressure that is causing this? Am I fucked?

The ignition coils are a bit old. So I bought a kit with the D585 and am wondering if it is worth installing them and try to continue the break-in (know how it sounds but I am grasping for straws here)

I reeeeaaaallly don't want to open it up again but I don't know if there are any other options.

 

Did you replace the oil control o-rings on the rotors?

Have you checked that your breather is OK. Of the oil pan area is pressurizing from blowby it can dump a lot of oil in short order?

Had a REW once that the irons were resurfaced and it always smoked after that... thought it was the iron surface. Turned out that there was a small hole in the rotor apex seal groove in the front rotor and was pissing oil out... when the rotors were lightened they somehow got a thun spot that were through or something.

 

Huh, I hadn't thought that the oil could be going through the breather hose into the combustion chamber. I checked the breather hose when the engine was running the first time after rebuild, but haven't checked it since. Will have a look this weekend. Thanks!

The oil control rings, scraper rings and corresponding o-rings and springs are all new. My rotors haven't been lightened and I inspected them quite thoroughly (hope I didn't miss anything).

My initial guess was that the increased oil pressure + resurfaced irons hadn't mated with the new oil control rings = oil leaking into the chambers. But that doesn't explain the sudden increase in oil consumption after 600 km...

 

While I don't think it's the root cause, breaking in on synthetic oil is not a good idea. You want cheap basic conventional oil that allows the seals and surfaces to wear, not glide over each others' peaks. Especially if you had resurfaced with 320 grit. I'm not an expert on resurfacing but 320 sounds way too coarse as a final finish :/

 

Did you see if its the oil metering pump that's faulty? Either way, there is a diagnosis procedure linked below.

https://rx8handbuch.de/esicont/en/sr...300103W18.html

 

edit: Double post, my bad.

 

I had a problem many years ago ( 1995),
rebuilt a RX4 13B BP, put in car,
ran it and it smoked badly,
reviewed workshop manual and realised I had put oil control ring springs in upside down,
pull apart and re assembled,
ran for years,
possibly still running now ,


anyhow, its a possibility

are you in Sweden?

 

Myon,

Check the OMP vacuum "mitigation" system. The actual oil injectors, and the one way valves in the banjo bolts. One or more may be bypassing and exposing the OMP lines to engine vacuum through the injectors themselves. Your oil issue may not be internal to the engine proper.

 

Agreed. This could be an OMP problem.

 

I don't see how a system designed to dribble small amounts of oil in over the course of an hour could even flow 2L of oil in 20 minutes.
That's a crazypants amount of flow for the narrow OMP plumbing.

 

I agree. I have seen 1 litre in 20 minutes at the track with the pump on max output.

I would bet first the lapping...

 

Loki, yes I agree that a finer finish would probably be more desirable. I was told that its fine enough because it will wear it self either way. But in retrospect I wish I had used finer grains towards the end, just for the sake of easing your mind if nothing else. It is also interesting what you say about the oil and break-in. I've thought the same thing, and was wondering if one should use a mineral oil with something like 0w10. What oil would you go with?

Sinkas, haha yeah I am in sweden xD How did you figure it out? Also I double, triple and quadruple-checked that the springs were in the place and orientation. Those springs together with the 2 piece apex seals+springs were the most scary parts of the rebuild, so I took my time to make sure it was made right. Reaally hope that isn't the issue here... But if everything else fails I'll disassemble it and have a look.

Regarding the OMP, it seemed like you need some kind of computer to connect and read the "MOP_POS"-value. How would one go about troubleshooting the OMP without that? I cleaned the nozzles and banjo-bolts with thinner and a soft brush. Had no idea about the one way valve. Are they located here:



Do you guys think there is any risk that I broke them while cleaning them? How can one know for sure if they are working?

All the vacuum lines are attached and none of them had any visible cracks. But assume that something here is fishy, how would one find out if the OMP is the culprit? I am thinking about disconnecting the OMP from the electrical system, or installing a 2-stroke-oil adapter and letting it draw air or just plug it... I have one of those lying around, not yet installed.

Thanks for all the responses btw, appreciate it a lot.

 

Edit: double post...

 

At Blackhawk Farms Raceway I used 1 qt in 3x20 minute sessions through a Sohn with reasonably increased output.

 

If the OMP, due to a defect in the vacuum check valve system, is exposed to vacuum, it will flow a surprising amount of oil. Just like if you "steam clean" your engine. You can go through a gallon of water at 2000 rpm in about 5 minutes.

The OMP lines are smaller, but there are 4 of them. Not the most likely possibility, but worth checking. There aren't a lot of ways an engine can use that much oil in that time period, the OMP system is one.

 

The M in OMP is for metered. Oil can't flow through it above the metered rate even if your engine was exposed to the vacuum of space.

OP, do you have any pictures of the rebuild process?It really sounds like poor sealing at the oil control rings.

Check if only one or both rotors have oil on the plugs? If both either 2+ sets of oil control rings failed or the problem is before the engine in the intake flow. If 1, you know the problem is limited to 1 seal/rotor.

It could be barfing oil into the intake and ingesting it that way.

 

Actually, oil can flow quite readily through the OMP with vacuum. And not a lot of vacuum. Sorry, Loki, that is incorrect. It is worth for the OP looking at, again not the most likely scenario, but worth ruling out before pulling an engine.

 

How is it going to pull it through the pump?

 

No idea, this would be pretty rare. If anything OMP failures generally stop putting oil in the engine. It’s a long shot but could try disconnecting the pump to see if it makes a difference. Running without the pump won’t hurt anything in the short term. At least just to rule it out before ripping the engine out.

 

I apologize that it seems I haven't responded, my replies are being delayed it seems. A respons from me from last weekend just popped up ; )

I took a lot of pictures of the rebuild process, but unfortunately not so many of the assemply of the rotors. Attached are the best pictures of the rotors after they had been assembled. We used white vaseline for all parts except for the oil control rings-o-rings, for them we used syntetic oil (because I read that vaseline makes the o-rings swell, but I guess that oil might do that as well.. I don't know)

Last weekend I put in d585 ignition coils and fired it up to get it out of winter storage, and it smoked quite a bit xD

• I also checked the plugs after running it for a while, both chambers are equally bad.
• No puffing from the oil refill-"hole" and nothing from the breather hose either. In the intake I could see a slightly shinier circle around the breather hose hole (some oil remnants). This circle was ~3 cm in diameter. Otherwise no visible oil, completely dry inside the intake.. I also disconnected the breather hose and attached a catch can and ran it for 10-15 mins, nothing ended up there.

So it seems there are to suspects left: OMP and lapping.

I'll disconnect the OMP this weekend and see what happens, I'll add some premix to be safe.

If it is the lapping, what can I do? Change to a mineral oil and restart the break-in? (I've been trying to get these as attachments, but they always end up here in the text... sorry)

 

Nice pics! Disconnecting the OMP completely wont hurt anything you have nothing to worry about in the short term. Worth it just to see if that's what's causing the excessive oil.

If its lapping you'll need to pull the engine and smooth it out more. I still think it could be the OMP though. From the pics it sure looks smooth enough to me.

 

The OMP is mechanically driven, you can't disconnect it. If you remove the electronic connection it will still flow oil at the idle rate and put you into limp mode. It's like 1000% not the OMP.


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Thanks Cayman!

It sounds like ruling out the OMP is a good idea before tearing down the engine ; )

Just for sake of science I'll disconnect it first and see what happens, but then I think that the best way of know for sure is to install the SOHN adapter I have lying around and either let it suck air or monitor the oil level of the separate tank. That should give a definitive answer.

I'll keep you updated!

 

Loki, you mentioned before the synthetic oil not being optimal for break-in. What oil do you use? Do you use any additives?

 

The way the OMP can flow oil in the quantity indicated is through vacuum. You can suck oil through the OMP with your mouth if you want to. I have done it. It is yucky.

If you want to rule it out in this case, electrically disconnecting it will not do this.

You can rule it out by just cracking open the banjo bolts at the OMP one at a time, with the engine running. Oil should flow out of each one slowly. If you hear air hissing upon opening one or more of them, then you have found your problem.

Engine vacuum can 1000% pull oil right through the OMP, if the atmospheric side of the system is clogged or otherwise mis-connected.

The likelihood is very low in your case, in my opinion, but better to do a 15-20 minute check than to have an "a-ha" moment while your engine is on the stand.

Or worse, you pull the engine, take it apart, and then find no reason. It's better to rule out the easy stuff early, even if it is not the most likely.

Is the oil consumption rate still as you reported before? It doesn't look like that much smoke for that much oil, in the picture.

I know it sounds condescending, but another thing I would check is my method of actually measuring the oil in the engine before I would pull it. I personally have done many incorrect things and wish I slowed down and rechecked my assumptions before moving forward.