M113, V8, oil pump pick up

[Uncle Benz]

I’ve seen a bit of discussion about this potential issue on some US forums and youtube for a while. I’ve recently bought back an SLK55 AMG, which I owned for a couple of years before selling it to a close friend. I used the car for a few trackdays, and my friend did a few with it too. There is a potential issue with a rubber O ring that seals the pickup tube into the oil pump. This had been nagging away in the back of my mind for a little while. The rear main oil seal had been weeping for a few months so I decided it was time to get that sorted out. It seemed a good opportunity to pull the engine out and go right through it.

As it turned out this was a good idea….

The O ring in question was pretty hard, and the pickup tube literally fell out of it when I unbolted the clamps.
It seems I caught this issue just in time!

The upper big end shells were almost worn to the copper!!

 

[Uncle Benz]

Certainly a timely move! All the lower shells were barely worn, as you’d expect…

But all the upper shells were worn, identically

The new O ring is a modified part. It’s green. This problem is undoubtedly exacerbated by high oil temperatures, and that goes hand in hand with track use, unfortunately.

 

[Cole@MBS]

Was that the same 55 which was on the track day when I was with you in your car G?? Didn’t suss that when I spoke to you yesterday!!! New shells will pull a tad more oil pressure as well!!

 

[Uncle Benz]

Was that the same 55 which was on the track day when I was with you in your car G?? Didn’t suss that when I spoke to you yesterday!!! New shells will pull a tad more oil pressure as well!!

Yup, same one. Seen a reasonable amount of track work. It’s never been thrashed, but certainly has been used as the manufacturer intended!

 

[ajlsl600]

Think on adding thermostat controlled oil cooler capability. I see a lot of hard O, . Rings, operating at 40c above ambient temps.. just had exactly the same on John deere transmission sucking air thru dried out o ring on pick up pipe shud be redesigned or have o ring end submersed in sump oil. Pump was wrecked.

 

[Uncle Benz]

It already has an external oil cooler with thermostat from the factory. I feel there are issues with the airflow to and from it though. I’ll be updating with this later…

 

[ajlsl600]

It already has an external oil cooler with thermostat from the factory. I feel there are issues with the airflow to and from it though. I’ll be updating with this later…

Does the extra cooler run on air flow alone or fan forced air?

 

[Uncle Benz]

Does the extra cooler run on air flow alone or fan forced air?

It doesn’t have a fan on it. It has a nice little duct to guide air in from beside the offside foglamp, but the back of it butts up against the inside of the arch liner. There’s nowhere for the air to get out. I’m going to do a seperate feature about this soon…

 

[Uncle Benz]

All closed up, ready to go back in on Saturday…

 

[Uncle Benz]

It’s back in, and running beautifully. The next job is already on the engine stand. I think the stand breathed a sigh of relief when it received this tiny little four

 

[bigasotonuk]

Hi,
I have read about this O ring failure on the american forums, though from the M113k perspective i always naively thought that the N/A M113 was not effected, and the Kompressor version was only effected by the higher engine temperatures of having the charger.
Did you only do the bottom end rebuild? Or did you take the heads off as well? As I have read a lot about potentially failling valve stem seals and the occasional failling head gaskets

 

[Uncle Benz]

Hi,
I have read about this O ring failure on the american forums, though from the M113k perspective i always naively thought that the N/A M113 was not effected, and the Kompressor version was only effected by the higher engine temperatures of having the charger.
Did you only do the bottom end rebuild? Or did you take the heads off as well? As I have read a lot about potentially failling valve stem seals and the occasional failling head gaskets

I didn’t Andy. The car uses no oil between services, and the plugs remain very clean. The stem seals don’t seem to be a problem, yet…
I didn’t touch the main bearings either. I did check the crankshaft endfloat with my dial gauge, and there was no problem with that. The fact that the bottom shell halves were like new, and all the wear on the upper shells was only on the high load area leads me to believe that lubrication was there, but not quite as much as was needed. Obviously the big ends is going to be where the most wear is shown. I didn’t have the time or inclination to do a full teardown and rebuild.
I have done an awful lot of big end bearing shells on BMW M engines, S50, S54 and S65. They are a lot worse usually than you see here. I’ve carried out full rebuilds on those occasionally, and the main bearings are always sound. My experience tells me this M113 will be fine for a good while yet. Regard this as an interim refresh

 

[Uncle Benz]

This is what you’ll frequently see with BMW S54 engines. I think you’ll agree I caught mine pretty well. My uppers weren’t actually down to the copper, but the white metal is so thin you can see the copper through it. You’ll see on the ones below how bright the copper is when they’re worn completely out.

 

[Uncle Benz]

The problem with the oil pick up O ring is best understood if you imagine sucking a drink through a straw, with a pinhole halfway up

 

[Uncle Benz]

And here’s a set from an S65 v8 M3 that Maahny’s team at Evolve changed this week. 85,000 mile car…