Top End or Total Rebuild

[aigel]

And I wanted to add that the stock rod bolts don't fly out in stock applications. Never heard of it. Yes, if you over-rev, they do, or in racing applications (maybe!).

George

[Henry Schmidt]

I had a customer a few years ago that had a 3.2 in a 76 VW bus.
The engine leaked everywhere so he asked me to reseal it.
Before starting I told him that low mileage or not I would recommend replacing the rods bolts because these engines have a week crank/rod combination that can be improved by ARP rod bolts. He decided that all he wanted was a valve job and reseal. (I wonder if he got advise on line?)
We did what he asked, Valve job, reseal.
183 miles later it spun a rod.

I wonder if the 183 miles was worth it?
No hype, no sale, just a true story.
Cheers guys

[Eagledriver]

I think it is a good idea to replace the rod bolts as well. That doesn't mean you have to take the bottom end apart if you don't want to.

-Andy

[88-diamondblue]

Thanks Mark. Learned a lot and with Wayne's book, PP forum and some professional advice it went for the most part smoothly. I am still having some issues with oil consumption which might require the engine to come out again. I was tired of doing it at the end and look forward to doing it again someday.

[aigel]

Originally posted by Henry Schmidt

183 miles later it spun a rod.

I wonder if the 183 miles was worth it?
No hype, no sale, just a true story.
Cheers guys

Come on Henry, how likely is that to happen? One in two? One in 100 or one in 10000? Not many of us who have been around a fraction of the engines that you have can recall a similar story.

This is like asking yourself if you are going to stay in bed, because some people have accidents when they leave the house to go to work ... Likely you go to work every day, because you know chances are pretty slim that anything happens.

I doubt statistics show that 3.2s sporadically spin rod bearings. Yes, you always have outliers and it shucks if you are the one.

Even after your horror story, I'd still not touch that bottom end on a relatively low mileage 3.2 that never was over-revved. As far as I am concerned those bolts are fine, as long as they are operated in the designed range.

If you can't sleep without new rod bolts, at least leave those pistons in the cylinders and don't bother them, assuming compression is good.

George

[Henry Schmidt]

Rods fail in 3.2 and 3.3 engine all the time with seemingly no explanation.
They have a higher failure rate than any Porsche engine in history. Two reasons, bad bolts and poor oiling.
If you dought it, try to buy a std/std 3.2 crank.

[aigel]

Originally posted by Henry Schmidt

If you dought it, try to buy a std/std 3.2 crank.

Good point! I am glad I skipped the 3.2 then.

George

[sww914]

I think that 3.2 spun a bearing due to it's outrage at being stuck back into the van. The engine didn't know what to expect the first time in, but after it was pulled out it got it's hopes up that it would make it back into a Porsche product, and after it was re-installed in the VW, it was so depressed that it had an emotional bearing breakdown. It will recover if it is put into a nurturing environment and recieves therapy, medication, and positive affirmations.
As far as the 3.2 in question, every time I've done something "just good enough for now," I've been sorry later. If your bank account allows it, go all the way.
You're contemplating an adjustable rate mortgage in a time of rising interest rates, you'll really just pay more later.

[Henry Schmidt]

Sometimes you just have to smile

Originally posted by sww914
I think that 3.2 spun a bearing due to it's outrage at being stuck back into the van. The engine didn't know what to expect the first time in, but after it was pulled out it got it's hopes up that it would make it back into a Porsche product, and after it was re-installed in the VW, it was so depressed that it had an emotional bearing breakdown. It will recover if it is put into a nurturing environment and recieves therapy, medication, and positive affirmations.
very clever, made me smile
As far as the 3.2 in question, every time I've done something "just good enough for now," I've been sorry later. If your bank account allows it, go all the way.
You're contemplating an adjustable rate mortgage in a time of rising interest rates, you'll really just pay more later. Well articulated

[zbph10]

After reading this post and being in the middle of my teardown for broken head studs I ordered Wayne's Engine Case Essentials Parts Super Kit to do the bottom end while I'm in there.

Since I don't have any history on the bottom end I'll sleep much better knowing everything was redone.

This post just cost me $811 in parts. Thanks a lot.

Brian

[sww914]

Good sleep isn't cheap.

[JeremyD]

and believe me, it ain't worth it - After it's all buttoned up you'll be kicking yourself for not doing a complete job.

[Dadofour]

Mark,

Do the engine rebuild yourself, and the real "extra" will be your time and labor. The bearings etc that you will replace will be chump change. There will be no unknowns.

My vote is the full boat.

Than

[Boxer 6]

Hi Than,

I'm leaning heavily in that direction.

Thanks!

Mark

[88911coupe]

I'm looking at new valve guides and read this through but still need some help/clarification. If you break it down to the crank do you just replace the rod bolts? What about the rod and main bearings? My confusion is compounded by the fact that the Porsche Parts and technical ref catalogue lists standard and .25 mm and .5 mm versions. how the heck do you know which ones to use or is this beyond a DIY task?
TIA

[sww914]

The bearing bores and the crank and rod journals are manufactured to even numbers. A rod journal may be 42mm (for example, I'm not sure of the exact dimension). If it's been machined it should be machined in .25mm increments, so it will be 41.75mm, or 41.5mm and a bearing bore may be 75mm, so the first boring will make it 75.25mm, the second 75.5mm, etc. So you can measure them and tell what bearings you need.

[88911coupe]

Is this to say that if it's never been bored you should just use standard bearings or should it be measured for wear regardless?

[sww914]

I think they should at least be checked by a machine shop, if you're not able to measure them that accurately.
Someone like Henry Schmidt will be able to tell you how often, if ever, different parts are worn to the point of needing machine work.