2.2/2.4 knocking

[swade]

Out for a drive today, sunny day for the first time in ages. Started to notice a knocking at 3K+ RPM very near the house on return trip, pulled into the driveway and shut down.
Definetly a rod knocking sound. I have not heard it before in a Porsche engine but have been around enough cars to recognize the sound.

While the engine was warm I did a compression test:
1. 195
2.

[swade]

Sorry about that, I somehow sent the post before I was done.

Cylinder
1. 195
2. 202
3. 210
4. 206
5. 209
6. 205

Took readings twice and they were very similar.

It seems the only way forward is to get to the rod ends and investigate. Is it always necessary to split the case? My engine does not leak a drop of oil and I would sure like to keep it that way.

I am pretty happy with the compression readings, I dont own a leak down tester but with the lowest cylinder 93% of the highest it seems all is well on the top end.

Engine is a 71 2.2E stroked to 2.4 9.6.1 compression with 40mm PMO's. I am happy with the configuration (except the knocking) no plans on building the motor up.

I am sure that I will have other questions and invite comments.

Wade

[Grady Clay]

Wade,

Rod knock? I hope not.

The clue will be to carefully inspect the sump screen.
The space between the aluminum screen support and the case is the most likely to collect debris.
Copper-colored pieces are bad.
Aluminum needs investigating.
Dark plastic chips are probably chain ramps.
Large objects probably fell in the engine.
Most other is probably ‘normal’ debris.

Cut apart your oil filter.
Rinse with lacquer thinner (or other) into a clean glass container.
Pour through a coffee filter and inspect.


You post 2.2/2.4, exactly what is the engine?
If it is a 2.2 with the 2.4 (70.4 mm) crankshaft, was the piston skirt-to-crankcase cut to fit?

Best,
Grady

[swade]

Grady,

I will have the oil sump off soon and take photos of any foreign objects. The oil was changed just 100 miles earlier. No debris on the magnet and nothing in the filter. I will look again this evening.

The engine has 35,000 miles on it.
-2.4 crank
-I cannot answer if the skirt to crankcase was cut to fit as I do not know, work done by PO but this would not show up 35,000 miles later but immediately I would think.

Thank you,

W

[swade]

Copper it is, I was pretty certain that it was bearing sounds. I have not cut the filter but will later. I will drop the engine, looking for a motor stand in the area. Splitting the case seems inevitable now.

W

[Grady Clay]

Wade,

Yes, classic bearing material. Too bad.
The good news is you caught it before something worse happened.

Why did this happen?

Best,
Grady

[swade]

Grady, I wish I could tell you. Fresh Swepco, new filter. Oil pressure has been strong...

W

[Grady Clay]

Wade,

From above:

You post 2.2/2.4, exactly what is the engine?
If it is a 2.2 with the 2.4 (70.4 mm) crankshaft, was the piston skirt-to-crankcase cut to fit?

If this is a 2.2 (or 2.0) case with a 2.4/2.7 crank & rods, carefully inspect for occasional light contact between a rod or piston skirt to the case.
This can cause a bearing failure.
Also inspect the head and top of piston for occasional light contact.

What P&Cs?
If Factory 2.7 (90 mm) the heads needed a bevel cut at the transition from the flat (sealing surface) to the hemispherical combustion chamber.
If aftermarket pistons (any size), carefully inspect for cylinder head contact.

Disassemble slowly and carefully.
You don’t want to miss something important.
One bearing failure is bad enough. Another after the rebuild is ….

Best,
Grady

[swade]

Grady,

Engine out, getting it up on a stand today. I will report with photo and part numbers off the P&C's, block, crank, etc.

Thanks for your help.

[kugelfischer]

Good luck with the teardown. Out of curiosity, what was your approximate oil pressure per 1000 RPM prior to the knocking? Would a drop in pressure precede a significant bearing failure?

I'm hoping the red fan isn't a sign of a MM build?

[swade]

Grady,

#1 rod bearing the culprit, crank out of round at that journal at least. I will spend some time getting numbers today.

Engine:
6210154 which is a 71 E 2.2 case engine with MFI but running carbs.
Pistons:
Mahle 84V51 RO2H no damage
Cylinders:
Mahle 84Z0 no damage
Head:
911 104306 no damage
Rod:
911 103 105
Crank:
D597887, number on OD of one web, I dont see any other numbers on the crank.

#1 Rod Journal





Measuring more this evening. Will run into town to look at a bore micrometer for the cylinders tomorrow.

Thanks,

Wade

[swade]

It has been bothering me to say the least that I could not find the reason for the bearing failure. I really looked thorough the case halves this evening and found a small aluminum piece with a dent on the end of it stuck in a corner and could not figure out where it came from. After looking at every piece of the engine interior I found that it was a plug from the crankshaft. That would easily explain the bearing failure. It also give me some hope that I am only looking at crank replacement/regrind, rod refurb/replacement and bearing shells besides all the gaskets, bolts etc that go with splitting the case. Obviosly everything has to be measured and evaluated but there is some hope. I cannot see doing anything with the pistons, cylinders and heads with the way the car drove and the strong even compression figures.



W

[Porboynz]

I understand that those plugs are removed to clean out the oil galleries after a crank grind. Sadly it seems the replacement plug(s) was not refitted securely and trouble came knocking. At least you now know the cause of the rod bearing failure. Extensive cleaning is now needed for the entire engine to flush out any remaining loose bearing material. The oil cooler needs particular cleaning attention. I had a similar failure and the crank was cracked as a result of the rod bearing failure allowing the rod to hammer at the journal. Good luck with the rebuild.

[swade]

Porboynz,

Yes, there are bits of copper bearing throughout the engine. I am cleaning and re-cleaning. I am trying to source a std/std 2.4 crank to replace the damaged one rather than have it ground. I just wouldnt trust it after this.

Moving forward, talking to machine shops, making parts list and getting great advice from the Pelican gang.

W