Crushed Oil Spray Bar

[wcover91]

I dropped the engine this past winter for general cleanup and reseal. While preparing for a valve adjustment I noticed a loose nut in the bottom of my driver side valve cover. Having checked everywhere in the Cam Housing all nuts are accounted for. My best guess is this could have been left in from the previous owners engine rebuild. (Not surprising compared to some of the other shoddy work I have encountered)

Regardless, I noticed that this nut appears to have come in contact with the oil spray bar at some point in the past and dented it. What do yall suggest? I was not planning on removing the Cam decks during this rebuild. I also don't want to remove the front timing chain housings. So the only way to access the spray bar would be from the rear freeze plugs.

Should I try to remove and replace the spray bar? I cant seem to find a replacement.

Should I try to remove and repair the spray bar?

Should I leave it in place and try to re-swage it open with a bar from the inside?

Should I just leave it be and give the bar a good cleaning?

[bkreigsr]

If the cam ramps look okay, and the lifters are not scored, I'd leave it be.

Messing with it might led to bigger problems.

From here, it looks like everything in there is getting a goodly supply of oil.

Bill K

[KTL]

Can you get a closer in-focus picture of the damage? It looks to me like the spray tube is gouged open. If so, that is the path of least resistance in the tube and most of the oil is gushing out at that point. That means the other tiny pinholes in the tube which spray the other cam lobes and valve springs are not getting good oil delivery. Also worth mentioning is the oil supply to the the larger holes that feed oil to the cam housing bores. These bores lube the cam "bearings" where the cam spins inside of the housing.

I personally would have a real hard time leaving that severely damaged tube. It would always be on my mind while driving the car. Especially when driving it at higher rpms like these engines are meant to be driven.

I have taken apart several of these cam housings, some of them being junk, and therefore I have some extra spray tubes. I'll gladly send you one to get this fixed up right.

[juanbenae]

as kevin may recall I found nearly the same damage on a spray tube during my build a few years back. the problem is removing a bent one likely will require cutting it and removing in small pieces as it will not slide just slide out of the races due to the deformation.

I bought another full tower,,, from kevin. thankz Kman!

[wcover91]

The picture may be deceiving but the tube is not gouged open. Just dented. I would guess it is 50% flow restricted. I think Juan is right, this tube would likely require cutting to remove due to the deformation.

Kevin, if you have a spare 911sc spray tube I would gladly take it off your hands. I suppose replacing it might be the best idea since I really hate having these little problems in the back of my mind while driving hard.

Anyone have any experience re-plugging with 1/8" NPT plugs? Seems pretty straightforward. Tap to depth and install with some blue loctite.

[john walker's workshop]

Cam towers are plentiful and dirt cheap. I'd just replace the tower. Going to come off anyway.

[trond]

I replugged mine with 1/8 NPT. Easy. Used yellow locktite btw

[KTL]

Yep Mr. T brings up a good point about removing the tube. You'll have to bend it fairly straight and cut it to get it out. Pulling out the tube is a bit fussy because they're installed pretty tight. But it's not terribly difficult.

I don't disagree with John Walker about replacing the housing because they remain to be very cheap. The only caution i'll add is that i've found the cam housing to be one of the most neglected and abused parts of the engine. So it is sometimes a crap shoot to find one that's not been molested. Careless people have either boogered up the valve cover gasket surfaces, scratched the crap out of the head sealing surface, or quite often you'll find the rocker shaft bores all gouged up. So just keep that in mind and ask for good pictures of those areas if you go for a used one.

I've done a few sets of the cam housings with 1/8" NPT plugs. One nice thing about doing this is that the existing hole in the ends of the cam housing is the perfect size for running in the 1/8" NPT tap. No drilling of the hole is required to tap it. You only need to drill the existing aluminum plug with a suitable size drill to tap the plug with threads and insert a screw to pull it out. I like to use an M6 screw, a large washer and a 10mm 1/4" drive socket as a hollow spacer. Run the screw into the new threaded hole and the plug pulls out very easily this way.

Plus, since you're taking out the tube anyway, it's a good situation for tapping the NPT plug holes. You have to run the tap into the hole far enough to make the hole deep/wide enough to make sure the plug seals tightly AND sits flush or below the surface of the hole. If you've got a regular lead-in tap, it's long enough that it will hit the end of the tube and smush it. So that's why it's best to have the tube removed when installing NPT plugs. And the NPT plugs should be steel because aluminum plugs are very easy to strip the hex tooling (because it's way too easy to overtighten tapered threads in my experience) and then it's stuck in there.

I don't like taking out the tube unless absolutely necessary because it's a tight fit and some tubes are tight enough that the tube gets scraped around the outside pretty good as you're coaxing it out. I've also noticed some tubes have some sealant inside the cam housing that ensures the cam bearing oiling holes do not leak oil. So that sealant adds a bit of resistance for the tube coming out. Just so it's clear what I mean by this, a leak there doesn't cause a problem in terms of it being a leak outside the engine. The oil leaks into an already "wet" part of the engine. It's just a matter of good practice to keep the oil in the tube and not have the oil wasted if the tube was allowed to leak out of the cam housing holes that its passing through. That's why I don't like removing the tube unless absolutely necessary.

The way i've done the tube removal is to tap the tube out from the end with a hammer and suitably sized drill bit that clears the ID of the hole, but is of course larger than the OD of the tube. Once the tube is tapped out far enough, you can use the cam bearing oil holes in the tube near the end as a way to make a T-handle in the end of the tube. I pass a pin punch or a drill bit through the oil holes and that gives me a way to evenly pull on the end of the tube. Then I patiently wiggle and slightly twist as I pull the tube out of the housing.

So after all that being said, THAT'S why JW recommends sourcing a good used housing! Saves you a lot of work for not a lot of money. Used housings are usually $200-$250 a pair or less.

[wcover91]

Thanks for the detailed feedback! The cams, rocker levers, and valves are in such good shape I wasn't planning on removing any of the top end. I was just gonna do a valve adjustment and close it back up until I noticed this crushed line. I am trying to avoid replacing the whole cam housing because that causes a lot more work that seems unnecessary at this point. Additionally, I wasn't planning on removing the timing chain housings so I wont be able to access the front freeze plugs. This means I wont be able to hammer the spray bars out with a drill bit as described.

I think the best I can do with the cam housing and timing chain housings in place would be to remove the rear freeze plugs, pull the spray bars out the rear (likely requiring some cutting of the crushed tube section), then replacing the bad spray bar, and re-plugging with a NPT.

What do yall think?

[john walker's workshop]

Bad idea.

[KTL]

Agreed with JW. Gotta suck it up and take the housing off to get the tube out and clean up the debris you cause by drilling out the plugs and cutting the tube.

Removing the cam housing is not all that hard. Nor is re-timing that cam. Sure it costs you some considerable time, some sealant and three inexpensive gaskets. But in the end you'll be sure you did it right. Who knows, you might find something else that needs fixing once you dig into the spray tube fix?

And in all honesty I think the NPT plug is something that people came up with as an alternate choice since 1/8" NPT tap and plugs are easy to come by. Whereas the replacement aluminum plug is something you have to source from Porsche or have a machinist turn out on a lathe. I really don't like taking out the tubes and the only reason I did it on my housings was because it was a racecar engine that I thought i'd service more often than normal and thus i'd want to take out the tubes again at some point. What I learned is that I think it's not a good idea to disturb these tubes any more than is absolutely necessary. So I think once you put a new tube in there, it ain't coming back out again. It's much easier to take out the old aluminum plug and replace with a new one. I have a handful of them in my nut & bolt organizers and I can send you a couple with the spray tube.

[LM3929]

where can I find the aluminum Plugs?

Thanks Lorne M.

[SBell]

Originally Posted by LM3929

where can I find the aluminum Plugs?

Thanks Lorne M.

I got them from Pelican. 90110537900

Sent from my SM-G991U using Tapatalk

[porschyard]

Originally Posted by LM3929

where can I find the aluminum Plugs?

Thanks Lorne M.

The tube plug is available from the dealer and is inexpensive. Part # is 901 105 379 00 Also the part # for the tube is 930 105 362 02 and the cam housing plug is part # 930 105 161 00 Richard