1988 Porsche 944 Track Toy

The oil, if diverted to the cooler, still has to go through the filter before it gets to the pressure sensor and the block.

So if the filter was basically dry, but the pressure sensor was pegged, how was that happening?

   Has anybody ever removed that entire assembly, and just connected AN fittings to the block where that assembly goes?

      Then you could get rid of the oil thermostat and set up a remote filter assembly.

         I never ran a oil thermostat on that fiesta, set up a oil temp gage and let it run for a little while before revving it or running hard.

          Are you sure the pressure sensor on that assembly is after the oil filter?

             If you got rid of that assembly and set up a remote filter, the oil would go from pump to cooler, to filter, at exit of filter, set up the pressure gage, from there the oil goes to the engine.  Keep it simple, you want to know the pressure that the bearings actually see. 

By using the Factory 951 setup, I thought I was keeping it simple. :-)

I took the pistons out and assessed the bearings and crank. The bearings weren't going to live long had they stayed, that's for sure.

These are 1 to 4 left to right, with the rod cap halves in the foreground. The closeup is the #2 rod cap bearing.

The crank journals are very nice with just a little staining that appears to want to rub off. A light polish will take care of that.

Pretty good considering it was sitting, bathed in milkshake, for 4 or 5 years. The "oil" that I cleaned off of them was really gooey. 

Before knocking that booger stuff off with a fingernail, and after:

The skirts on the piston are far better than the last one...

No scratches that would cause concern.

Perfect bores. I couldn't find a scratch on which I could even try to catch a fingernail.

Lots of cleaning and organizing to do in preparation for assembly.

I started to clean off the carbon buildup on the piston when I quickly realized I wasn't going to be able to do it mechanically. On rennlist one guy had used paint stripper with fabulous results. 

The picture above is after 12 hours, scraped a bit with some plastic cardstock, and now reapplied. 

It wasn't until this point that I discovered the piston tolerance group for the #2 piston is "3"! The others are all "2".

Now I know from the factory manual that they can be mixed on the same block, but I've never seen it before.

What's wild about this is that the factory manuals available online don't even list a Tolerance Group 3. I couldn't find mention of it on the forums either, although it's a tricky thing to search for.

But sure enough, the carpet matches the drapes:

If you are curious about which tolerance groups are on YOUR block, they're visible without taking off the head. They're peeking out on these extra tabs near the oil galleys.

Have you seen one (three) before?

CrookedRacer said:

If you are curious about which tolerance groups are on YOUR block, they're visible without taking off the head. They're peeking out on these extra tabs near the oil galleys.

Have you seen one (three) before?

Very interesting. I'll have to poke around my car and see if I can find that.

You know when you spend all evening cleaning and scraping and at the end you feel like nothing really got done?

Well, last night was one of those nights. I took pictures afterwards but it’s not impressive:

Then tonight I finished the pistons up and readied everything for assembly. I still have to clean those last two bores and gap the rings first.

Also, I’ll probably plastigage the oil clearances before I assemble pistons...

Here is the obligatory plastigage check with the fresh bearings.

My understanding is that if it is unacceptably off, there’s nothing you could do but take it to a machinist. But it is cheap peace of mind.

Fortunately, it came out just fine. I’m gonna send it.

Also, I need to buy a pair of reading glasses for every room in the house. They’ll all end up in the garage, of course.

So I finished assembling the bottom end, and carefully torqued the 20 oil pan screws. And that night I realized I couldn’t remember torquing the oil pickup tube bolts. Kind of important.

So I went back in and realized the tube was in the way of the 17mm nut so it had to be hand tightened. Thus I couldn’t recall torquing it!

I took the nut off, put some loctite on it, tightened it back up, and closed it up again. I feel better about that.

Then I turned my attention to the head. My head looked pretty good, but there was evidence the #2 valves had hit the piston. So I took them off and checked them...

Rolling them on the countertop wasn’t conclusive. I guess I should have rolled the stems with the valves hanging off the countertop, but the drill method revealed the problem. Both were pretty wobbly.

So I took two valves from the donor engine’s head. I cleaned them up and then a miracle happened:

That’s right, I actually found this tube of compound, and this valve lapping tool, in two different places in my basement. This build is truly blessed, and it’s time to buy a lottery ticket.

I bought these things in 2011 to rebuild a flat head Briggs & Stratton go-kart motor. Wow!

After lapping the valves, I think they’ll do ok. Time to clean up the deck.

*snaps fingers*

Installation of the valves went really well. I installed new valve guide seals on just the two that I put in. All others I left alone. Then I did a rough check with a straight edge of the valve height, and they definitely were right in line with all the others.

I was really happy I wasn’t going to have to grind anything or worry too much  about cam clearance.

So I put the head on the block and torqued it down,

Just a couple more photos...

Here I discovered one of the spring retainers in the new head was cracked and probably ready to fail...

And here my nephew is doing the initial 15 ft-lb torque on the head bolts using his grandfather's old Craftsman torque wrench. Good times.

I’m sorry for taking so long to post, but I’ve been busy getting this car ready for HyperFest!

It makes the long story shorter, so I guess that’s a plus. Most of the remaining preparation was fairly uneventful, so you didn’t miss much.

The engine got finished by Friday, and I scooted it under the engine bay. I had it hoisted into place on Sunday, attached all the things, and those other things, and had it ready to try to start by Tuesday afternoon. 

I got it started on Tuesday evening and made the call: I was GO for HyperFest.

Lifting the engine into place in the rain in my driveway on Saturday.

The state of things on Sunday:

Monday night, stuff was hooked up and everything was ready except priming the oil pump, so I did that on Tuesday morning when I had some light...

I wrapped tape around one end of this hose to fatten it up. I took out the Oil Pressure Relief Valve (OPRV) and stuffed it in there, turned on my wet-vac, and put the wet-vac hose against the funnel until I saw oil coming into the hose. It’s easy to control because you can remove the vacuum hose very easily.

When starting it up on Tuesday afternoon, it took very little time to achieve oil pressure.

On Wednesday I did a little testing in my neighborhood as I loaded the trailer, and Thursday I headed to the track after work.

Friday I started the car and ran it up to temp a few times. The valve lifters were starting to quiet down. It was actually sounding really good. I had alignment strings and turn-plates at my disposal, but I didn’t use them.

Saturday morning I pull out all my safety gear, and I have brought the wrong helmet. My racing helmet is five hours away, and warmup is in an hour. So I pretty much had to buy a new one. Ugh. Thanks TMI Motorsports! At least the prices are the same at the track as they are online. And you carried the same brand of helmet I had before, so I didn’t have to waste a lot of time getting the right fit.

Warmup went well. I kept the revs below 5500 for the most part, never higher than 6000.

Qualifying went well. I kept the revs low, and ended up with a 2:23 something which is around where my best is at that track in this car, so that was encouraging.

Then I got out there for the race. That’s when things went badly.

I again kept the revs low. There’s no sense in winding it out when there’s not much more power to be had, even if fourth gear is a little tall.

My job out there, because of so few other drivers in my class, was to stay out of other classes’ races. So I had a clean lap or two but got stuck behind a Honda Challenge 4 car while I (we) let the leading H2 cars by.

Then on the front straight I checked my gauges as I usually do, and noticed the water temp was slightly elevated (like at Summit Point). The oil pressure gauge was pegged. I listened and it sounded “different”. I was just past pit-in, and I didn’t want to go all the way around the track again, so I pulled off after Turn 2 and headed across the grass to the EV access, getting my car behind the tire wall before shutting it down.

The engine now sounds like it’s running without oil.

My weekend was done. Again. That’s two race weekends, two dead engines.

It’s time to take some time to question my interest in and commitment to road-racing.

Damn. Hadn't looked at your thread in a couple weeks and was so encouraged until the last post...

Third time's a charm!

I've been hashing out the potential issues with 944 folks on Rennlist (my thread title begins with "Ouch.")

One of the readers there asked about my tow strap. I guess I never documented it here, so here goes.

I bought mine from the good people at Track Monkey Apparel..
https://www.trackmonkeyapparel.com/c...abelt-tow-hook

I think the soft loops are a positive trend that will ultimately become a rules-driven requirement. Hard pointy things sticking out of the front of cars aren't as safe as no things sticking out.

All I did was bolt it directly to the underside of the bumper with a metric grade 8.8 bolt.  There were some holes already there from where the previous tow hook had been mounted. I widened one of them a little bit so that the larger bolt would fit. I've been towed with it TOO MANY TIMES :-( and never had a problem.

Oh man! Please don’t give up!  

Sounds like it could be the same issue, yes?   Whatever that might be. 

So in the past few months I've been enjoying my summer, working on other stuff, and pretty much not missing wrenching on the car. I missed racing, but I don't miss the constant, ever-present fear that the car won't survive a race weekend.

One week in July, I took the dash out and covered it with faux suede. It looks pretty awful. Then my phone filled up and decided it would be best to delete everything on itself. So I don't have pictures of the process of making my dash look awful.

All summer long, I tried to get a rough estimate from an outfit that does VW 1.8T swaps on Porsche 944's. They were very nice on the phone, when I could catch them on the phone, but they constantly brushed me off and never once returned my calls or emails. Not a good sign. I guess I should just be thankful they don't have my car while they're not returning calls.

I do get pangs of guilt as I walk past the covered race car every day.

So this weekend I bought a short block from an '87 944 NA that's in OK shape (it's awesome to have a local resource like Just Joshin') and it's time to get the car running again. I might make the final event of the year, if I'm quick about it.

Ove the past couple weeks, I've been moving forward with the plan to get to the bottom of what happened at VIR's Hyperfest in May. I didn't get the car ready in time for the last NASA event at Summit Point, but I did go out to the track to watch my friends battle it out in ST6. And indeed they did! On Sunday, Kevin and Tim were side by side across the start-finish line, with a difference of .0035 seconds.

At 110mph, that's about 6.2 inches.

Anyway, I was inspired to get my car as strong as possible for the spring. And maybe move my transciever forward a little.

I got the car where it needs to go: the usual operating theatre outside my garage door. But at the same time, I also bought a panda:

hit this link, you won't regret it:   WE BOUGHT A PANDA!
 

I thought about doing a build thread on the panda, but this link to my website should do:  https://www.dogparkracing.com/panda

Anyway, I killed two birds with one stone - I got the car in position and I got my trailer out of the way of panda's path to her new home.

On with the forensics!

Veterans Day was a beautiful warm sunny day - perfect for wrenching. I took everything out of the engine bay including the head, which was perfect. The pistons and cylinders also looked perfect, fortunately.

Now, at this point, I grabbed a socket and tried to see if there was any play in the connecting rod bearing by turning the crank back and forth.

First I turned it forth, and then when I turned it back, the crank bolt loosened with nearly zero resistance (less than the resistance of the pistons, that is). I really think I could have turned the bolt off with just the socket without the ratchet handle! It may have even been loose, and my turning the crank might have made it as tight as it was.

This is BAD, because that thing is supposed to be torqued down to 145 ft-lbs. The GOOD news is this discovery might explain everything that happened!!!

A loose crank bolt on a 944 means there might not have been enough pressure on the oil pump spline sleeve, which is NOT keyed to the crankshaft. For reference, the oil pump spline looks like these:

Without enough pressure on it, this ring might not turn the oil pump, which could mean low, intermittent, or no oil pressure! A low oil pressure event could mean overheating indications, bearing failure, loss of power, and to complete the symptoms, the alternator pulley/timing gear assembly might have been flopping around, making that huge racket.

ALL of these could be explained by this one discovery, which made me hopeful. I don't like rebuilding engines without knowing I'm doing something to fix the problem.

Then it got really cold, and it wasn't until yesterday that I got the engine out of the car so I could look at the bottom end.

It never seems to take as long to do these things as I obsess that they will. I got this engine out in just a couple hours.

Then I got it on a stand, and got to work...

With the oil pan off, I could certainly get the #2 bearing to wiggle a lot more than the other three. When I removed the rod cap I caught a whiff of burnt oil, and the bearings came out looking like this:

These are in HORRIBLE shape - and it tells me that I shut down the engine just in time. I do believe that if I had driven these one more lap, they would have disintegrated and spun.

The crankshaft fared pretty well, but I think what I'll have to do this time is take both of my crankshafts to the machinist, evaluate the health of each one, and choose one to put back in. (I didn't have time for that when I threw this engine in here in May)

I'm really happy that this very valuable 1988 block with its 10.1:1 high-compression pistons is still in perfect shape. I'm 99% sure I'll be building it up for the spring.

My buddy took this pic of me preparing to drop the engine yesterday. It's starting to get cooooold!

Can you pin/key the shaft to the crank?

In reply to jfryjfry :

I don't know. It would require machining equipment I don't have, that's for sure. I will ask the machinist if they ever do that.