Cat 511

[Mike L]

one of my customers owns this machine. Serial number is 51100276. Powered by a C9. Runs fine, no codes. While running at 1700 rpm’s he has 28psi of oil pressure and it runs about 176 degrees. He dropped it to low idle today and walked the wood lot. At low idle he has 35 psi of oil pressure and it warmed up to 195 degrees. I couldn’t come up with a reason. the oil change is fresh as I just put injector cups in it a few weeks ago. Does anyone have any experience with this. It has t really been an issue but my customer wants to be ahead on this before it becomes a problem.

 

[mg2361]

For the temperature, does it have a hydraulically driven fan that could have an issue? Don't know why the engine oil pressure would be higher though.

 

[Mike L]

I believe it just has a belt driven fan. I had thought of that too.the oil pressure is my bigger concern.

 

[hvy 1ton]

My random and non-professional thoughts:
pressure relief in the oil pump is sticking open at higher engine speeds
and
engine fan clutch is locked in and I assume it's currently cold in Maine

 

[Northern mb]

How certain are you that the gauge is reading correct? Have you verified it with a different gauge?

 

[Mike L]

Hvy 1ton, those are some pretty good thoughts. I haven’t gone to investigate yet but that will be at the top of my list.

northern mb, this past summer he had a low oil pressure alarm come in and I verified his oil pressure was in spec with a manual gauge. we replaced the sending unit and he hasn’t had any issues until he got some fuel dilution and I replaced the injector cups and resealed the injectors.

 

[Former Wrench]

I like the thought of checking the pressure relief valve. That would either solve the issue or rule out a probable cause.

 

[Zac93]

These things love to crack engine oil pickup tubes. Then they fall off one day. Perhaps it's sucking air and doing some weird stuff?

 

[Mike L]

so I’m still dealing with the fluctuation in oil pressure but I believe it has to do with fuel dilution. Originally he had dilution and he was told it was injector cups. I always thought a failed cup would put fuel into the coolant but I replaced the cups at his request. The injector o rings had seen better days and I assumed that was his problem. he doesn’t run the machine a lot so it has been a slow problem. His oil level started rising and I returned to look at it. I followed the troubleshooting on cat sis and they mentioned the fuel inlet fitting could possibly be cracked. The inlet wasn’t cracked but the check valve on the ret line was destroyed. I really don’t know why he didn’t have a starting issue. I replaced that and changed his oil. He has put 37 hours on it since then and now his oil pressure is fluctuating again and the oil is light and runny. At this point according to sis, my last options are the transfer pump seal or possibly a cracked head. The transfer pump has a new updated part and can’t be replaced without replacing the heui pump. We were quoted at $2800 for the parts. I put some fuel dye in the fuel filter and ran it and then removed the valve cover think it may be an injector but I saw no dye around the injectors. I’ll have to make another trip down and I‘m looking for any ideas or tricks you guys may have. I find problems every time I go but obviously I haven’t found the culprit.

 

[Vetech63]

I wouldn’t be worried about the temperature difference, a faster speed on the fan moves a lot more air. In a cold climate condition, the temp diving lower than the thermostat setting could just be specific conditions.
Have you compared the oil pressure reading from a mechanical gauge to what the operator temp gauge is reading? Are they comparable? What engine oil is being used? Have you tried any different viscosity oil? Engine oil cooler equipped? Is the cooler water or air cooled? Cat oil filters? Had any previous engine work been done before this issue came up initially?

 

[Mike L]

I’m not very concerned about the coolant temp. No engine work. Cat 15w40 and cat filter. I did the oil change. Last summer he had a low oil pressure code and I checked it with a mechanical gauge. It was in spec. He replaced the sending unit and I didn’t hear anything about it for 3-4 months. Then the oil dilution started. Then he noticed the low coolant temps. Machine has 7500 hours on it and has never had the engine apart. Engine has a water cooled oil cooler. I’m convinced that his oil pressure issue is directly related to the dilution but I’m struggling to find the source. Every time I’m there I find an issue but haven’t found the trouble maker yet.

 

[Nige]

Have you looked at the internals of the head of the oil filter.?

We had low oil pressure warning light issues on a number of C13 engines in excavators once the engines got plenty of hours on them (10k+) but only when it was coming up close to oil change time. The light would flicker and sound the warning if the engine was idled when it was well warmed up.

What we found was that the filter bypass and high pressure bypass spools were made of plastic and for some reason were wearing into the aluminium body of the filter head. It took a replacement head, new spools, & springs to fix the problem.