Built B6 keeps leaking from camshaft seals need help
 

Hi Guys,

Last year ive built my 1.6 B6 for my turbo project in my NB.

The engine was bored and honed to fit oversized wiseco 8.5:1 and rings gapped for max 1,5 bar of boost, this all done by a reputable and experienced (on miata engines) machine shop here in the Netherlands.
also K1 forged rods ARP headstuds, coolant re-route, ACL main and crankshaft bearings and a boundry stage 1 oil pump with no shims has been fitted.

The car hasnt been turboed yet as I first wanted the engine to be 100% correct before throwing boost at it.

After setting the engine up on the dyno (ME221) it made a healthy 115 BHP so far so good i would think.

However....

Ever since the engine was fitted to the car an oil leak kept on appearing on the front side of the engine, which did not come from the new crankshaft seal on the front, ive eventually narrowed it down to the camshaft seals.
After replacing them with OEM ones (first victor reinz) were fitted the problem persisted so ive taken the camshafts out and found that there was a little wearmark of the seal, see photo
Then ive placed 2 speedisleeves from SKF to fix these wearmarkt and fitted 2 new OEM seals with a little RTV on the outer edge.

Initially this seemed to work however after my trackday of yesterday with 3x 20 minutes runs i found that again there was a **** pool of oil laying beneath the engine, nice detail is that running the car to work for 2 weeks 140km a day did not trigger any leakage.

I am about to think the crankcase ventilation is not up to the job, however the pcv valve does what it is suppose to do and the other vent is venting to the atmosphere via an filter.
Ive havent got an idea yet of the oil pressure as i still have to fit the sensor however after 6000km and 5 trackdays it should be somewhere right otherwise i would be rebuilding again :-P
Also the engine does not consume any oil.

I did do a compression test and a leakdown test today and the leakdown did not show more than 2% and the compression test (cold) were as followed:

1. 8.7 bar
2. 8.7 bar
3. 8.5 bar
4. 8.8 bar

I am about to do a crankcase pressure test somewhere this week, does anyone know what an acceptable crankcase pressure is with the OEM crankcase ventilation?
Would forged pistons and gapped rings make more crankcase pressure than original?

If someone has other suggestions that would be great as I am running out of ideas here


thanks!

When an engine builder is sizing cylinders for pistons on a forced induction build, sometimes they will keep the tolerances a little loose because of the higher cylinder temperatures that can be experienced. The last thing you want is a piston seizing in the cylinder bore. Being built a little loose can cause some extra blowby.

I enlarged both crankcase vents and routed large hoses to a vented catch can with great success. I also enlarged the internal passages in the valve cover.

There's a great thread on this forum on crankcase ventilation, so please look for it.

The Boundary pumps come with an o-ring to seal the outlet to the block. If not present or not seated or was cut during installation, it can leak around the timing belt at the top of the pump. That would sling oil everywhere inside the timing cover.

I've never heard of problems with leaks around front cam seals here, and you can see how long ago I joined the forum. That does not mean it can't happen.

Ideal crankcase pressure is zero or less than zero. This might make you think that the PCV is valuable to you. It is not. The PCV will be useless once you add a turbo because it closes completely when you go into boost. That would then leave one small opening for all of the additional crankcase pressure. Turbos do not like crankcase pressure and will cause you to burn oil.

Oil vapor has a lower octane rating than fuel so ingesting oil vapor will cause your engine to detonate more readily. Always avoid routing oil vapor into a turbocharged engine.

Those wear marks don't look terrible. Polishing the surface gently may improve sealing. It is also possible to seat the seals further in or slightly further out in the head so that the lip of the seal touches a slightly different spot on the camshaft. It doesn't take much.

8.7 BAR is about 126 psi on your compression test, for others reading this.

Solution found
 

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So I think I’ve finally found what it is.

ive removed the cam gears and re-fitted the camcover with the rtv in the edges of the caps, then I pressures the crank with a compressor (only .5bar) and found air seeping past the caps.
i also think ive replaced the cam seals and the speedisleeves for nothing but I’ll take it as a lesson
https://cimg1.ibsrv.net/gimg/www.mia...09d5fac67.jpeg

I try to keep my crankcase pressure at .5psi or less, 7psi seems excessive, make sure you're only testing at 1-2psi (.07-.14bar). If you're actually hitting 7psi internal, somethings fucked, but I realize you're only testing.

Yeah, I would leak at 7psi also, even without my Miata.

When replacing the seals the cam bearing caps have to be removed. This prevents damage to the cam seal journals and allows a small amount of sealant to be applied to the front edge of the parting line between the cap and cyl. head. I have many cams that are damaged by the seals being pried out with screw drivers and other tools. The ring end gap is increased on FI applications to prevent the ring ends from butting. This will increase the blow by and crankcase pressure.