964 3.6l Engine Rebuild

[NoEardGoat]

Well, I wasn't planning on doing a rebuild. In fact that is the reason why I bought this engine so that I would be able to "drop a good engine in" rather than rebuild my 3.0L. The inevitable happened and I now have spent a lot more money and still will need to rebuild an engine. Paying $6500 for an 3.6l engine that needs new rings and valve job at least really sucks!!!!!!! I would have just rebuilt the 3.0L if I would have known this. Maybe I will get "lucky" and all I need is to re ring and valve job this 3.6l.

I did a compression leak down test to all the cylinders. I used a tool that I made. When using the tool I set it @ 100 psi. disconnected and then connected the hose w/ spark plug fitting to the tool and got the following results. I noticed that the gauge on the regulator dipped along with the connection to the hose. Is this normal?

Here are the compression leak down test results:

1: 9% Air heard through crankcase breather past rings.

2: 12-13% Air heard through exhaust and rings.

3: 8% Air heard past rings

4: 11% Air heard past rings

5: 14% Air heard through exhaust and rings

6: 56% Air heard through exhaust and rings


Fawk! This much couldn't be from valves out of adjustment could it?

What is my next step?
What is the best case scenario?
Here is what I am thinking clean/degrease the engine before I remove the valve covers. What is a good waterproof way to seal up the intake and exhaust openings with the manifolds removed?
After cleaning, remove valve covers and inspect valvetrain. Then remove cam covers, cams, cam tower, and then heads. Inspect. Then remove pistons and cylinders, inspect.

Here is the original link I started in the tech forum; 964 3.6l conversion 911sc
There will be many pictures to follow............. Wish me luck! It seems I need it.

I will try and talk to the seller and see what, if any, reimbursement I can get. Any advice?

Trying to keep a smile on,

-Emerson

[MBEngineering]

HI Emerson
what year engine is the 3.6, engine No'/type as the early engines had seal and piston/ring prob's??. befor you dive in .

regards mike

[NoEardGoat]

62N50637 It should have the rings. I checked the serial number. I was aware of this problem. Thanks.

[NoEardGoat]

I did my leakdown test with a cold engine that has sat and been transported for the last 3 weeks. Does this make the test invalid?

I just talked to a mechanic, not Porsche, that said this needs to be done to a hot engine. He suggested that I clean the engine up check the valves, especially cyl. #6. And set everything to spec and reinstall everything, then install the motor and run 2 compression tests, one with a hot engine and dry and the other with a tablespoon of oil added through the spark plug hole.

Is this good advice???
Could my engine be ok, and just a valve out of adjustment?

[MBEngineering]

HI NoEardGoat
Have you had the engine fitted?, if not, how long as the engine been stud before you got it, as the exhaust valve seat/valve could have some rust build up and cause the leakage, try turning the engine over a few times with the plugs out and then test again, if you have the rocker covers of you could try backing the rocker off on that cylinder and with a soft punch and a LIGHT tap on the end of the valve stem it may just re-seat the valve in the rust, you could do this with the cylinder leakage tester connected and you can then see if you have made any difference, if not you then know the heads will have to come off to inspect?

regards mike

[NoEardGoat]

Thanks Mike. That is a great idea. The engine has been sitting for 3+ weeks now, but ran in the car before it was removed. I don't have the conversion stuff yet to install in to the car.

I pulled off the valve covers and took a look and everything looks good. No excessive cam wear on #6, I checked the valve clearances on #6 and the intake was easy for the .004 tool to enter and the exhaust was a little tight, but the .004 went all the way in.

Could the valve not seating all the way and still be reading @ .004 clearance? I guess so if the actual clearance is much greater, right?

I will take a closer look @ the valve and seat when open. Then do the soft tapping method if still suggested with the valve clearances talked about above.

I don't remember if I stated this, but the motor came out of 1992 C2 with tiptronic trans. w/ 48k miles.
-Emerson

[NoEardGoat]

Ok, no I seem to be talking to myself, but I will post some pics of what I discovered today. I was examining the exhaust port on the cylinders 4-6 and noticed that #6, with 50% leak, has a weird casting shape or material missing or something? Here is a picture of the #6 Exhaust port and one of the other normal 5 exhaust ports.

Is this a factory deal or is this head messed up?

#6

#5

[304065]

looks like missing ceramic port liner

[NoEardGoat]

Originally Posted by john_cramer

looks like missing ceramic port liner

Missing or broken?

What is this caused by?

What do I need to do to fix it?

[NoEardGoat]

Help!

[MBEngineering]

HI NoEardGoat

"What do I need to do to fix it?"

replace the cylinder head!!

regards mike

[NoEardGoat]

OK, when replacing the cylinder head would you think I am ok to just replace it. Or would you replace rings, valve job on rest of heads, etc. The rest of the cylinder's leak down numbers aren't too bad considering they were done on a cold engine. I would like to keep it cheap, but want to be confident in this engine for miles to come.

[ianc]

Hi Goat,

I don't know how valid your results are for the leakdown test since it was done on a cold engine.

However, it seems to me that you would be better off just to bite the bullet and go the whole hog with guides, valves as needed, and possibly rings.

Taking the engine out, cleaning it, and tearing it down are such gargantuan tasks that you will be crushed if you work your way though this project only to find that you need to do it all again. Spend the extra money now and have the confidence.

Also, when you go to reassemble the engine, check the leakdowns again when you've got it built up to the longblock. If there are any problems, better to know about them beforehand...

Good luck,

ianc

[NoEardGoat]

I just looked at the part numbers off the cylinder heads. 5 of the heads all have: 22012 B7 (90/11) One has: 22012 B6 (90/9) Guess which one has the different set of numbers. That's right good old problematic #6. Could this just be because the #6 head is different to accommodate the power steering pump that attaches to it?

Side note: Do I need any special tools to remove the cam gear? Porsche tool #9191?

I really appreciate the help.

-Emerson

[NoEardGoat]

I messed with the engine a little more and since the motor has been sitting for a while I now have 100% leakage on #6. I tapped on the exhaust valve and got it to down to 80%, but now further. I will probably end up pulling the head off as well as the others and refresh the top end.

[NoEardGoat]

Update:
I have since pulled apart the engine removing everything down to the rods. The pistons and cylinders look good, rod bushings look good, bearings feel tight, pistons pins removed easily. All the heads look good except #6. The cam gear was easy to remove on the pass side, but difficult on the driver side. The small sprocket had to be removed with a pulley tool, where the pass side slid right off? I plan on replacing a this troublesome gear. The pass side cam has a bad lobe on the intake of one cylinder. I need to inspect the other cam a little closer. The #2 intake rocker has a small spot that should be cleaned up. Cam chain and all the gears, intermediate shaft gear, etc. all look good.

I will take the valves out of the heads this weekend after I borrow a valve compression tool and inspect the heads further.

I am having trouble locating a single cylinder head at a reasonable price. But I talked with Henry from Supertec today and he said that he wouldn't worry about the miss ceramic port liner too much. If I can get a head cheap enough, less than 200.00, I will replace it otherwise I'll take Henry's advice and just clean them up.

I plan on replacing the rings, gaskets, seals, fixing the nasty spots on the cam, and a valve job. Considering upgrading to some Titanium springs and keepers. I probably should rebuild and replace the belt in the dual dist. as well. And of course clean and paint everything to make it purrty!

[ianc]

Sounds like you're going about things the right way. Keep us informed of your progess with some pics!

ianc

[kirkf]

Someone else may disagree with me on this, but it is my understanding that missing pieces of the ceramic port liner is quite common and it can be ignored.

If you are taking the motor apart, be sure to change the rod bolts. They are the weakest link in the motor. ARP would be my choice.

Kirk

[ischmitz]

I was told the same thing: The ceramic liner is often cracked and/or missing on these engines. Nothing to worrry about too much. However, make sure you inspect all valve guides and valve stems carefully. They are known to need help on these engines because the ran very hot in the orginal calrs. I had my heads redone completely when I did my rebuilt. Money wisely spent.

Cheers,
Ingo

[NoEardGoat]

My project hasn't died!!! It has just been on major hold.

I took the motor down to what is in the case, rods, crank, bearings, etc. Everything feels real smooth and tight. I talked with the local Porsche mechanic and he said he wouldn't bother to replace anyting on the lower end if it felt and looked good. The motor only had 47k miles on it. I have got advice from others on this forum to go ahead and take the case apart and replace the rod bolts with after market ones, which is apparently a weak point in this motor. This would raise the rebulild cost significantly because I would have to buy new bearings, have the bolts properly stretched, and reaseal the case. Advice???

For now I am going back to working on the conversion wiring, and getting the fuel lines ready. Wish me luck!!!