removing cam boxes

[Alan L]

I am trying to prise the cam boxes off the heads on a 2.7 911(replacing oil tubes/seals). They wont budge. I suspect the sealant the PO has used. I am scared to hit them any harder for fear of breaking them. All the rockers and nuts are off. I've double/triple checked.
What to do now?
Thanks
Alan

[boyt911sc]

Originally Posted by Alan L

I am trying to prise the cam boxes off the heads on a 2.7 911(replacing oil tubes/seals). They wont budge. I suspect the sealant the PO has used. I am scared to hit them any harder for fear of breaking them. All the rockers and nuts are off. I've double/triple checked.
What to do now?
Thanks
Alan

Alan,

I almost damaged my cam box last week when I was removing it. There is one particulat nut I left behind which was hidden in plain view. I just did not look very carefully inside to notice it. HTH.

Tony

[tom1394racing]

Once you have all the nuts off, rest the cam tower head assembly on your workbench with a pair of short 2X4's under the outside heads so the middle head is free to drop. I put the barrel nuts loosely on the four corner studs of the middle head to protect the threads. I then tap (bang) on the corner studs of the middle head with a hammer and round punch in a criss-cross pattern until the head loosens from the cam tower. They usually separate with only gentle tapping.

You can then repeat this process for the two outside heads.

[Alan L]

OK, but we are trying to leave the heads on the engine. Waynes book also suggests removing all together - but what we are trying to do is replace the oil return tubes.
We have no particular need to remove the heads.
Looks like the job is a whole lot trickier this way.
Regards
Alan

[tom1394racing]

If you are trying to replace the oil return tubes without removing the heads, you should be using the expandable return tubes.

P/N - 930-107-040-01-M59

http://www.pelicanparts.com/catalog/shopcart/911M/POR_911M_ENGoil_pg1.htm#item3

[john walker's workshop]

lots of unnecessary labor going on here. you can do all 4 tubes in 1/2 hour without disassembling anything. air pump 3.0 cars need the left exchanger removed and the air distribution tube loosened.

[Alan L]

We are trying to remove some expandable tubes - leaking like mad. Also several other serious oil leaks around cam box etc.
Just trying to tidy all the oil leaks.
My friends car. He has been parking it with ice cream containers under each side to catch all the oil.
I told him it was time we pulled the motor and tidied it up. Did leak down, one cylinder not good - inlet valve. So, removing one head. All other leak downs good. So no need to pull the other heads. Timing chains fully stretched (no travel left on tensioners), clutch plate near gone etc.
Just struggling to free the cam boxes. Have they ever broken being hit too hard?
Alan

[john walker's workshop]

you should probably remove the whole head/cam tower assemblies as a unit and then pop off each head on the workbench. just 12 head nuts per side and less potential damage. besides, if one head is bad, the rest are not far behind. in addition, head to cam tower leaks are common, so you can reseal all the heads and eliminate that problem too.

[docrodg]

Agree with John, normal engine wear is constant on all parts and the other heads probably not far behind. Plus, an added bonus is you can then lap the valves and polish the heads. Not to mention get a good eyeball on cylinder wear. Agree with you on oil tubes, the expanders do not seem to last as long, and can be finicky.

If cam housings are still stubborn after removing heads and tapping down and out just remember... there is no problem a suitable amount of high explosive cannot handle.

[Alan L]

OK then guys. Was just trying to disturb as little as possible. The leakdowns on other cylinders were 98-100%.
So far in our search for oil leaks (and hot running 2.7) have found thermostat stuck shut, oil cooler completely blocked with oil gunk, 1 blocked spray bar hole, clutch plate flush to rivets.
The car was imported from Japan, history unknown. But the crankcase has been split before. EVERYTHING has been sealed with RTV - crankcase, rocker bushes, cam boxes, camseals, chain towers, oil return drain tubes etc.
I bought a 930 in from Japan a couple years ago (for track). Same deal - rtv everywhere that could be used.
The 2.7 even had about a half pound of it wrapped around the oil line feed at bottom of crankcase - and the pipe flopped around on the RTV. There was no sealing washer on the crankcase - just a loose union and RTV.
The workmanship in Japan is lousy.
Regards
Alan

[docrodg]

Ouch! that many oil problems I would skip on the top end and go for the whole engine rebuild... there could be some rather nasty bearings in there and other clogged passages. May not be too bad yet, but further use could cause the crank, rods, and pistons to lose some precious oil circulation and that will be a lot more expensive than a gasket kit and loctite.

I never understood the fascination with RTV, worked on quite a few of these engines before and each time had to clean off RTV... just too sloppy of a sealant to use on one of these engines. There is a reason the loctite is used by the factory, and I am not about to second guess all the engineers and years of experience Porsche has. I have always found excess rtv in various oil passages after it's use and am willing to bet your engine has it too.

[Alan L]

I agree about the RTV. It has its places, but not in a Porsche engine. I rebuilt my SC from the crank up, no RTV, and no oil leaks. I think it is just a sloppy/lazy way out of doing a proper job.
Oil pressure is excellent. I dont think my mate (nor I) was expecting to split the crankcase.
We may take our chances on that - but I agree about bits of RTV circulating in an engine.
I have pointed this out to my mate - bit of RTV strings hanging off gaskets internally. He wont use any more on the cam covers I'm sure.
Regards
Alan

[Alan L]

We are going to pull the cam boxes with the heads. My mate has bit the bullet.
Taking your advice John.
Alan