1989 964 C4 Engine re-build

[sgoldberg]

Today while driving to work, I was in third gear at about 6000 rpm when I tried to shift to 4th gear and wound up back in second... My car lost power wound on the side of the road and would not start, Although she cracked very strongly. I had my car towed home. I was told by a few different shops that the rocker arms are probably snaped and the valve may be bent. I have been given price ranges to get the car back to OEM stock format in the range of about 5 - 6.5k. I understand that is a complete top engine re-build.

My question, once you have the engine out what are the good upgrades to have done at that point? Should I just have 3.8 jugs put on? New Race cam, Port and polish the heads? I'm not really sure what the cost are on such upgrades and what the profomance increases I could expect from such upgrades. Anyone have any thoughts on what my best rout would be?

I live on Long Island New York anyone have any experience with an race engine builders out in these parts? I'm open to your suggestions and comments.

Thanks for your time,

Sheldon

[sms1305]

Sorry to hear about your troubles. I have an early '89 C4, too.
I recently put late style 3.6L P/Cs in and had my heads cut to accomodate gaskets. I like the C-2 sport grind, but probably wouldn't do it again for a daily driver. I would definitely upgrade the rod bolts, but not sure I would use ARP for my head studs again. There is a lot of authority here that suggests the 993 head studs are more than sufficient. It's not clear whether you over-reved or not, but I might be thinking about doing the bottom end, too. Good luck!

[purplehaze]

Ouch! Really sorry to hear that.

I did the same thing at a track; it broke rockers, bent all the exh valves, etc.

Bill Rudtner is right in your back yard. Dangerous man. Give him a ring.

Rudtner's European Auto Inc /
Rudtners Racing
16 Saint Johns Place
Freeport, NY
516-378-8769

Good luck!

Glenn

[sgoldberg]

Glenn,

Bill Rudtner is Dangerous meaning good or Bad? I have some good things about him as well as, a few not so good. Can give me any experience you have had with Bill? Would it be worth while to upgrade to a 3.8 jugs?

[purplehaze]

Sheldon,

I'm sorry. My sense of humor often doesn't translate.

I meant good. Dangerous, as in he holds the keys to candy-land (more HP, modifications, upgrades, and all that is sinfully fun). He knows his stuff, and has been a good source of diagnostic help and suggestions for me, and many others on the board here. I've not had him do rebuilds, but others here have, and have splurged for some serious upgrades (3.8 and 3.9 liter stuff). He just modified some crankshaft bearings for me.

I'm sure you'll find all shops have pros and cons. Just give him a ring and talk through your goals.

If you really want someone to just do the top end, keep it stock, and do it the most cost efficient way, I have someone in CT I'd recommend.

[sgoldberg]

Glenn,

Got it Thanks...I am torn between getting aggressive with the rebuild or putting it back to stock. I guess its the cost factor. 6k for a top end rebuild verus 10-15k for a 3.8 with all of the bells and whistles. The questions is ...IS it worth the upgrade? and money?

Sheldon

[Jeff Alton]

IF your P/C set are in spec, you can send the cylinders to Steve at Rennsport Systems and he can have them moddified to accept the 993 sealing ring for a very reasoable fee. He has done a set for me a couple of years ago that worked perfect.

I have only heard good things about Rudtners and Bill and Tim both post on these forums a fair bit. They helped me a lot with the EFI set up on my 3.4 and I am yet to spend a dime with them. They were superb.

Cheers

[sgoldberg]

Jeff,

Thanks - I did speak with Bill today. He seems to know his stuff and he is not pushy at all. I have spoke with a few big name shop here locally and a lot of them want to know my budget. To which I respond what does it cost to do a full rebuild? and than I add the upgrades on to the discussion to see their ideas...WOW how the opinions differ. Some what to do turbos others say do 3.8. The list is endless, I am trying to just make sense of it all. I want a complete rebuild and I do want some upgrades.

I'm just trying to figure if an upgrade to a 3.8 would be the way to go and at what cost?

[sww914]

There are times when a missed shift doesn't mean a rebuild. Porsche put the cast rockers in most of these engines so that they might break rather than bend the valves. You can do a leakdown test and it will tell you if the valves are bent. If they aren't, you can just replace the broken rockers and go.
One of my customers let his buddy (with $$$) share his car last year 3 times. 3 trips to the track, 3 missed shifts. Once, it broke 2 rockers, I drove up to Laguna, did a leakdown, replaced 2 broken rockers and they finished the weekend. The next time- missed shift, 4 broken rockers, bad leakdown.
It spun one of the cam nuts loose, cleaned the teeth off of the camshaft sprocket mounting flange, ruined the cam sprocket, bent 5 exhaust valves, broke the guide boss on one head, destroyed one camshaft lubrication tube, and I think that's pretty much it.
The next time it only bent the exhaust valves and broke 3 rockers, but I was finally able to talk him into racing valve springs with titanium retainers that he hadn't wanted to spend on previously. Only one missed shift since then, no damage.
I don't know what kind of rockers 964's have, it may be that none of this applies, but I really like to hear myself type.

[sgoldberg]

Originally Posted by sww914

There are times when a missed shift doesn't mean a rebuild. Porsche put the cast rockers in most of these engines so that they might break rather than bend the valves. You can do a leakdown test and it will tell you if the valves are bent. If they aren't, you can just replace the broken rockers and go.
One of my customers let his buddy (with $$$) share his car last year 3 times. 3 trips to the track, 3 missed shifts. Once, it broke 2 rockers, I drove up to Laguna, did a leakdown, replaced 2 broken rockers and they finished the weekend. The next time- missed shift, 4 broken rockers, bad leakdown.
It spun one of the cam nuts loose, cleaned the teeth off of the camshaft sprocket mounting flange, ruined the cam sprocket, bent 5 exhaust valves, broke the guide boss on one head, destroyed one camshaft lubrication tube, and I think that's pretty much it.
The next time it only bent the exhaust valves and broke 3 rockers, but I was finally able to talk him into racing valve springs with titanium retainers that he hadn't wanted to spend on previously. Only one missed shift since then, no damage.
I don't know what kind of rockers 964's have, it may be that none of this applies, but I really like to hear myself type.

Thanks for the advice! There may still be some hope! How do I do a leak down test in my driveway? What do I need and how would I do it? If the results go well maybe I could get rid of my depression! If not than I can futher prepare for my massive expense. Thansk again for your help!

[ischmitz]

Sorry to hear about your event. I think your connecting rod bolts are stressed beyond usage if you over-reved the engine. 964 are known for con-rod bolts to be a weak link.

This is why raising the rev limit is one way to eventually stress them to the point where they let go. Damage to them is accumulative since they keep stretching. Eventually, one becomes loose and you have a catastrophic failure. So I would definitely consider changing and/or upgrading to ARP bolts while the engine is out. They can be changed without splitting the case once the head and cylinders/pistons are off. However, the best way is to use a stretch gauge when installing the ARP bolts.

When I rebuilt my 3.6 I opted for not splitting the case and had the ARP bolts installed with the torque method one at a time. Nothing wrong with that in itself. However, even though this is unrelated now I am paying the price with a leaking #8 nose bearing. Arrrgh - I wish I would have gone all the way and done the full rebuilt....

Ingo

[sww914]

Our benevolent benefactor Wayne describes a leakdown test here- http://www.pelicanparts.com/techarticles/mult_Engine_Rebuild/mult_engine_rebuild-2.htm
You need a tool to remove the spark plugs, a leakdown tester, a tool to remove the distributor cap, a tool to turn the engine over, and the ability to find TDC on each cylinder. To lock the engine in place, you can just put it in gear and apply the parking brake each time you reach TDC.
I bought a $40.00 leakdown tester at Harbor freight once, I took it back and bought a better one from a tool truck.

[sgoldberg]

Thanks for the info. Do you know if there are services that come to you to do the leakdown test?

Thanks,

[sww914]

I don't think so. If you were about 3000 miles closer to me I'd stop by and help you.

[sgoldberg]

LOL thanks for the offer

Someone mentioned it could be just the distributor cap - any thoughts?

[sgoldberg]

I spoke with a local Porsche shop. They suggested that the distributor may have been broken when I over-reved the car. The reason being is that the car doesn't run and my undertsanding is that even if values are bent or rocker are broken the car would still run. just not very well. Does that make any sense, why thoguthts and suggestion please.

Thanks,

[Aurel]

Very easy to pull the distributor and see if it is broken. Two nuts. You can mark its position for future reference. You can also remove your cam covers and see what the rockers look like.

Aurel

[Crashly]

Hey guys why not do a simple compression test? If the rockers are snapped then there will be no compression. The tool is only 20 dollars and it only takes a little over an hour to do yourself. If you do find a piston with no compression then that is where the search begins. I have had a few different vehicles leave me dead on the side of the highway and most of them have been electrical related, however none of them were combined with a missed shift. Dont be afrtaid to tear into it yourself, one way to look at the problem is that at this point it would really be hard to make the problem any worse.

[sgoldberg]

Great Point ...if it is just rockers that is pretty easy to fix...Meaning cheap...$$$ otherwise it will be more costly doing an entire top end rebuild...

[sgoldberg]

Thanks for everyone input and advice. I have taken the to a local shop, Rudtner's European Auto Inc - Rudtners Racing aka Wild Bill Rudtner. So after reviewing my options I decided to purchase a 1993 RSA motor with 40k on it. Wild Bill has agreed to install it and hopefully I will back on the streets very soon. When this car is finished I will probably sell this car and try and find a C2 to create a monster or maybe finds someone old project car have some fun. will see...Thanks again for all of the advice.

Sheldon