coltj

Hi,
My first new thread posting as a "newbie". So the engine of the '96 C4(47K miles) is all apart at the mechanic's shop for a top-to-bottom overhaul. Went over to the shop today to look at the pieces. Mechanic(well-experienced with 993s) shows me a "problem" he says he has never seen before. The oil port nozzle("that sprays the back of the pistons") for 5 of the 6 cylinders is recessed at least 1/2"(12mm) back into the block. Only the #4 cylinder port is flush with the surface of the block. I've attached a few photos that show a "wide-angle" view of cylinders 4 & 5 and then close-up of their respective ports. Anyone seen or heard of this before. I'm very impressed with the knowledge of the 993 forum Rennlisters; that's why I joined. Thanks in advance for your help.

mr_bock

Question, why a tear down at only 47k? Was there a problem showing? Earlier mods?

coltj

I purchased the car late-November. PPI showed 12-20% compression loss in 2 cylinders. Stethescope indicated bad exhuast valves. Seller negotiated favorably based on PPI report.

coltj

Post-script to last-message: No previous mods; stock all the way. No engine work. Know the seller well and knew he took care of the car(e.g 3K oil change interval w/ Mobil 1....)

Steve Weiner-Rennsport Systems

Based on what I've seen, I'd say that it looks like the nozzles were installed that way at the time of manufacture.

coltj

Thanks Steve. My thought too that they must have been installed that way. I know the engine hasn't been apart before and I douibt the nozzles moved even during 8+ years of use. As I understand it the nozzles should be reasonably flush with the block. Any option whether this is a problem that should be addressed now that the engine is apart? More labor since the mechanic will have to split the case. One concern is the oil supply to 5 of the 6 cylinders. Granted, I have to admit that the car appears to have run well for the previous owner in this condition. Not obvious to me that the 2 bad exhaust valves would be associated with this. Should I contact Stuttgart to get their opinion? Thanks.

JasonAndreas

Who is doing the rebuild?

coltj

EPE is doing the rebuild.

JasonAndreas

If Jerry has a concern about potential oil supply problems I had have him fix it, he has way more direct experience servicing 993s than anyone on the 993 forum and 90% of the work is already is done so its a LOT cheaper to just do it now rather then later.

coltj

Post script: C4 is back together and running fine. Followed Jerry's advice to leave the oil nozzles as is. Really didn't want to crack the case. The 5 recessed nozzles have 2mm orifices, the one flush nozzle has 1.5mm orifice. Clearly both nozzle types appear capable of supplying ample oil as the engine ran without any problems for the previous 40K miles. Never able to find/contact the original owner to verify if he did any engine work during the 3 years/7K miles he owned the car.

One other intertesting anomaly. Jerry found that there was one exhuast rocker on the intake side. He did replace that.

Assuming no previous engine work, I'm still wondering about the findings. Bad day in Quality Control at Zuffenhausen??

Assuming the

SinVancouver

Just for reference can I ask what was replaced in the rebuild, did you upgrade any parts or just replace with OEM and, of course, how much was the work in the end..

As we all head towards this type of work its nice to have some idea of how its gone for others..

I am especially interested in if people are considering upgrading to third-party parts for longevity or just going OEM.

Also I am wondering if we are approaching a time where it may be best to do the work sooner than later.. as the cars age the parts seem to become harder to get and/or more expensive..

Thanks for any info you feel comfortable revealing

Cheers,
Scott.

coltj

The invoice is at home so I can't list all the details now. Basically I stayed with all stock/OEM parts. Head was reground, new rings, seals, new valve guides, cleaned SAI ports .... Mechanics verified "ovality"(or lack of) of the cylinders. Again, I'll get the details from the invoice.

I did replace the clutch(stock, no not the RS with LWF, as I don't have an unlimited budget) while the engine was out(engine has to come out to replace clutch in a C4/C4S...).