New 951 Owner

[tedg04]

Hi all. I just picked up a 86 951, and am proud to finally be in the Porsche family. In any case, she has a leaking cam tower gasket; which will require quite a bit of work to replace. I'm thinking of doing the timing belt, balance shaft belts, water pump, and other front end oil seals all at the same time. My question is on whether or not I should do rod bearings. I've never heard of the problem before my dad mentioned it to me. I have maintenance records for the car that show a timing belt and water pump were done 40k miles ago in 1999; but no where does it mention getting into the bottom end of the motor. The car was tracked occasionally by the original owner, but not a dedicated track car. It now has 155k miles and appears to be very healthy (autothority chip, otherwise stock).

What do the owners say, should I just bite the bullet and do all the front end stuff and get the bottom end done? Or can I wait at least until the next oil change? If I do the rod bearings, am I okay just buying replacement ones? Or do I need to measure the rods to get an accurate size?

Obligatory pictures:

[suedeworthey]

If you can afford it, do it all at once... If not, I'd suggest the belts and water pump, then the bearings. Just my opinion... Either issue (spun bearing or broken timing belt) can cause serious damage to the engine.

[tedg04]

Originally Posted by suedeworthey

If you can afford it, do it all at once... If not, I'd suggest the belts and water pump, then the bearings. Just my opinion... Either issue (spun bearing or broken timing belt) can cause serious damage to the engine.

Thanks for the reply. I guess I was just wondering how prevalent the rod bearing failures were.

[Komenda Fan]

Sorry I don't have any worthwhile advice on doing the bearings, but I love the colour combination on your car. Welcome to the family!

These are amazingly practical cars, I daily drive mine if it's not snowing. Just came back from a weekend camping at Mosport for the Historic Grand Prix. Car swallowed all the camping gear, made the journey in comfort, and then I got to watch a bunch of 951s fight it out with 911s, vettes, an M1, etc. Great car.

[billy mild]

Start running Brad Penn 20w-50 oil ASAP in the summer and 10w-40 in the winter. This will help with the bearing issue.

[AaronM]

Originally Posted by tedg04

I have maintenance records for the car that show a timing belt and water pump were done 40k miles ago in 1999

Do the timing and balance shaft belts NOW. They're 10 years (and 10,000 miles) overdue.

The belts need to be done every 3 years or 30,000 miles. I'd go ahead and do the water pump too just out of worry about the age and how little the car was driven.

[fb111]

My cam tower gasket has been leaking since I purchased my Turbo S. Its gotten pretty nasty as the oil is dripping on number one exhaust header. I figured what the hell, just loosen both allen head bolts nearest the front corner and retighten. They were kind of a ***** to loosen but retightening has worked. The stink is gone!!

[suedeworthey]

Originally Posted by tedg04

Thanks for the reply. I guess I was just wondering how prevalent the rod bearing failures were.

It all depends on where the car is, how it's driven, and how often. I have read (on some 944/951 forum/site/etc... probably this forum) that if you're over 150k it's a good idea. I would do it, or at least start budgeting for it in the near future. If you can do it yourself, it will save you loads of $$$, but cost loads of time.

If the PO raced/autocrossed/otherwise tracked the car, it might be a good idea to do it sooner. Lindsey Racing sells a 3 piece crossmember that would make the job much easier if you ever wanted to replace them again...

+1 for AaronM's comment. Do the timing and balance shaft ASAP, and replace the water pump while you're at it (better safe than sorry).

[suedeworthey]

Originally Posted by fb111

My cam tower gasket has been leaking since I purchased my Turbo S. Its gotten pretty nasty as the oil is dripping on number one exhaust header. I figured what the hell, just loosen both allen head bolts nearest the front corner and retighten. They were kind of a ***** to loosen but retightening has worked. The stink is gone!!

I need to try that... I am tired of smelling burnt oil... I presume you did it in the car (i.e. no cam tower removal)?

[fb111]

Just loosened a bolt on each side of the leak and retightened. I think the key is to loosen first. They are pretty difficult to break free.

[suedeworthey]

Originally Posted by fb111

Just loosened a bolt on each side of the leak and retightened. I think the key is to loosen first. They are pretty difficult to break free.

Thanks. In an attempt to stop jacking this thread (sorry tedg04), I replied in my original thread about my burning oil issue.

Strange Clutch Issue and Burning Oil Smell...

That's a nice buy tedg04!

[89-944NA]

Once you have done your cam and balance shaft belts (and rollers) and water pump, a good indication of the bearing condition is to bring the car to operating temperature, and check the oil pressure at idle. If the pressure is below 2 bar, you should change the bearings.

Another easy check for the condition of the bearings is to carefully cut open the old oil filter, pass a magnet through the folds and look for metal slivers, next, do a visual check, looking for bronze colored particals. The bearings have a babbitt coating that the crank and rods contact, bronze is the lining under the babbitt, and provides a small safety margin before the crank/rods contact the steel bearing shell and damage results.

Be aware that to change the bearings with the engine in the car is a major process, requiring suspending the engine inplace (suspend from the top), removing the front control arms, the complete exhaust system (including the cross-over pipe), removing the cross-member and engine mounts (this is why you need to support the engine FROM THE TOP!), then removing the oil pan. Chilton's Shop Labor Guide calls for 16 hours to replace the oil pan gasket, add 3.5 hours to change the bearings (assuming that the crank does not require polishing or undersizing), and that is using a shop lift, add lots more time if you are doing this in your garage, laying on your back.

I have found this tool invaluable for suspending the engine:

www.harborfreight.com/automotive-motorcycle/lifts-stands/1000-lb-capacity-engine-support-bar-96524.html

If you decide to replace the bearings, you should wait and remove a bearing FIRST to make sure of the size you will need (Standard or undersized...bearing shells will be marked as to the size). If you purchase the bearings first, then discover you need a different size....well you know the return drill...and lost time.

As for the cam and balance shaft belts, yes they are WAY to old to attempt to even start the engine, but for some reason there seems to be MANY mis-conseptions on belt mileage, the most recent factory recommendation is 45,000 miles on the cam and balance shaft belts.

Many on this board (myself included) have adopted a simple "calendar" for belt and water pump changes. I change my belts every OTHER Memorial Day Weekend (every 2 years regardless of mileage) and the water pump gets changed every SECOND belt change (4 years). I use Memorial Day, because it was an easy day to remember....and I just happened to do my first belt change that weekend...so I've been doing it that weekend ever since.

Check these links:

Periodic Maintenance Schedule

Timing Belts

Good luck, have fun, and welcome to the boards.

[tedg04]

Thanks for all the replies guys. Sounds like the pump and belts need to be done ASAP. Bummer since I have a drive to Big Fork Montana next weekend I would like to take it on (picturesque 4hr drive in Northern MT). The car holds GREAT oil pressure, over 5bar at startup, and hot as I can get it it's almost 3 bar at idle and back to 5bar running, with 20w-50 in it.

I knew you had to remove the cross member and suspend the engine, I didn't know yoy had to remove the entire exhaust. While I am somewhat mechanically inclined, I think I'll leave that to my mechanic.

[89-944NA]

exhaust is easy, it's the control arms that will get ya. Sure you can mark them and get them back to close to the proper alignment, but I prefer to have the alignment redone after removing the a-arms.

You can leave the headers on (I suppose, I've never tried to though), but removing them gives you a lot more room to work. Rest of the exhaust removal is just pretty much for room if the car is on jackstands.

[tedg04]

Originally Posted by 89-944NA

exhaust is easy, it's the control arms that will get ya. Sure you can mark them and get them back to close to the proper alignment, but I prefer to have the alignment redone after removing the a-arms.

Fair enough, but I don't see an alignment as such a big deal. There's a great place here in Spokane that will do a quality 4 wheel alignment for $70 or so. Removing and re-installing the A Arms is a different story.

[nize]

i have never heard of rod bearing issues, even on cars with +200k miles, unless coolant got into the crank case.

[89-944NA]

Originally Posted by nize

i have never heard of rod bearing issues, even on cars with +200k miles, unless coolant got into the crank case.

+1 Sold the 89NA with 280,000 miles, and the bottom end was never opened, still had great oil pressure.

[txhokie4life]

We've lost two #2's on our 944 NA engines racing them.

Also pulled the bearings on a 2nd car that had just finished about 40 track hours,
and they were wearing. We're pushing 48 hours on our #1 race car and
we'll pull the bearings over the summer before the fall season hits.

On my 928 with 120k+ miles, I pulled the bearings when I bought it and #2 and #6 were wearing
and this was normal driving as best as I know the last 10yr history on the car.

All PITAs to do -- but cheaper and less work than a new engine.

Mike

[89-944NA]

I have heard that #2 is most likely the one to go first in cars that see a lot of track time due to oil starvation. A friend made a trap door baffle for his 951 race engine, and has a few seasons on the engine with no starvation problems.

[AaronM]

Originally Posted by nize

i have never heard of rod bearing issues, even on cars with +200k miles, unless coolant got into the crank case.

I've heard it a lot for cars that are heavily tracked. By "heavily tracked" I don't necessarily mean tracked often, but rather tracked by drivers who were capable of pushing the cars fully and sustaining extended periods of high-g cornering. From what I understand, you have to be pushing the car pretty hard (harder than the average driver does during a DE day) for the issue to show up, but there are issues with the #2 rod bearing seeing reduced oil flow if the pump sucks some air.