Cat 320L low oil pressure alarm

[Logan]

could that be a spring seat? like maybe from the relief valve spring?

When you ran it and measured zero oil pressure, was the relief valve installed?

Yep valve was back in. I spoke to a cat guy who said the pressure valve between the filter cartridge and oil pick up was showing a cir clip on his screen, so i dropped it out, there was a washer, spring and a metal mushroom shaped thing with a long stalk. Had obviously seen better days but no sign of broken cir clips or a cir clip having been anywhere near any of it. It was screwed on quite tight. I put it back on about half as tight and it broke 3/4's of the way up the thread, possibly because of the spring wearing the inside of the valve plug, or possibly logger error. Circlip is not like I have seen before, has no ears, the end that isn't broken has a square slot where you'd expect a round hole or ear to be.

 

[Logan]

There is a secondary relief valve inside the sump. It is screwed into the underside of the block, vertically. You should check this as well.

Yeah I just broke that. Thanks though. When you say check it, is it supposed to just have the bits mentioned above i.e. "there was a washer, spring and a metal mushroom shaped thing with a long stalk" Also got told to check a valve on the filter housing and behind the oil pump so will get to those when it gets light again.

 

[Cmark]

Yeah I just broke that. Thanks though. When you say check it, is it supposed to just have the bits mentioned above i.e. "there was a washer, spring and a metal mushroom shaped thing with a long stalk" Also got told to check a valve on the filter housing and behind the oil pump so will get to those when it gets light again.

Lol. How the heck did you manage to break it?? Anyhow, I feel your pain bro.

Yes, it's just a plain spring and poppet valve sort of affair.

If you're really coming to a dead end on this, I would be trying to pressurise the oil galleries with compressed air to see if you're dumping flow somewhere you shouldn't.

Are you absolutely sure you got your pressure gauge check right? because to suddenly lose oil pressure on a previously good running engine and not find a load of bits in the sump is a rare occurrence indeed.

 

[Logan]

Thanks. Found 4 bits of white metal in the sump too, but no filings or anything, looked like something left over from partial rebuild a couple thousand hours ago according to insurance guy. Also found bits of a hard gasket, probably 1/4 of a teaspoon at most. And about the same in flexible sealant. That cir clip or maybe C clip, that's what I find alarming. One parts guy reckoned the only place you'd find a cir clip in the oil system is in the fuel pump, but I don't know if it would be fed with a 5/8th oil supply line? Or bigger. Will measure in the morning. Can anyone find reference to a cir clip/s in any 3066 manuals?

 

[Nige]

Ok, lets be clear we are talking about 2 different valves here. One is the oil bypass valve, installed vertically up into the cylinder block inside the oil pan. That is the one that is supposed to have the 83.5mm long spring inside it that I mentioned earlier. This comprises the 5I-7643 Valve (11), the aforementioned 5I-7640 Spring (10), 9J-2089 washer (13), and 5I-7644 Plug (12).


The other is the oil pressure relief valve (#14 in this diagram) installed horizontally into the cylinder block from the outside not far away from the engine oil filter. The valve is a 094-7205 up to engine S/N 7JK11273 and 5I-8066 for engines after that. The gasket is a 5B-5947.

 

[Logan]

Thanks Nige, any info or care to hazard a guess on the cir clip? My engine is slightly different to the diagram in that there is another 2 valves in addition to those you mention. One screws vertically down into the top of the oil filter housing, the other on an angle behind the oil pump cover. I don't fully understand how these work but gather there is just springs, sleeves and either mushrooms or big ball bearings in them but not cir clips. s'cuse the logger talk please I'm supposed to be cutting down trees.

 

[Logan]

ok found major cracks in oil pickup, will post pic, is this what could cause zero pressure? crack is 3/4 of the way round the pipe and is not far off snapping as its started travelling diagonally down the pipe. I am applying pressure to open crack for the photo. Didn't see it before as its on the weld and it was shocking weather but wifey reminded me to do a thorough inspection and there we have the blighter. (Thanks to Wifey. And to those telling me it may well be a pickup issue.) The big brace above the pickup was broken off at the block plus been repaired before and brace is also cracked by the bolt on at the pickup filter. presume this allowed non standard movement and stress to occur at the other end where crack in pipe at weld occurred. So could the cir clip be some random insert from a not very present mechanic at past rebuild?

 

[Nige]

Sucking air at that point could easily give you no (or at least very low) oil pressure. The thing is that welded joint is always above the oil level in the pan.

Remember the parts manual only shows one thing at a time. Let me go looking for the other valves you mention an I will post some illustrations. From your description one of them sounds like the oil filter bypass valve, designed to open if the oil filter gets blocked to ensure the engine gets oil to all the critical parts.

I wouldn't try to repair that pickup tube if the brace is broken as well. I assume you mean the brace closest to where your crack is, not the longer one at the strainer end that is listed separately..?

I would believe that any or all the material, metallic and otherwise, that you found in the oil pan could have been from previous repairs.

 

[mitch504]

It looks like that crack is at the top of the pipe, if so, I bet that's your problem. It'll suck air instead of oil.

Now, you have a real problem....

Your wife is the reason you found it; I doubt any of us can help you with that one, good luck, anyhow.

 

[Nige]

Now, you have a real problem....

Your wife is the reason you found it; I doubt any of us can help you with that one, good luck, anyhow.

I can say without fear of contradiction that you are never going to hear the end of this................

 

[Logan]

Sucking air at that point could easily give you no (or at least very low) oil pressure. The thing is that welded joint is always above the oil level in the pan.

Remember the parts manual only shows one thing at a time. Let me go looking for the other valves you mention an I will post some illustrations. From your description one of them sounds like the oil filter bypass valve, designed to open if the oil filter gets blocked to ensure the engine gets oil to all the critical parts.

I wouldn't try to repair that pickup tube if the brace is broken as well. I assume you mean the brace closest to where your crack is, not the longer one at the strainer end that is listed separately..?

I would believe that any or all the material, metallic and otherwise, that you found in the oil pan could have been from previous repairs.

Thanks Nige, to clarify it was the brace at the strainer end that was broken off at the block. I am a bit reluctant to weld it or the pipe, and I enjoy welding. It will come down to whether the meow parts blokes here are seeing the world thru gold tinted glasses or not. I would feel much better knowing there was a brand new one in there thats for sure. I hope to post some happier pix when we get the old girl going again and thanks very much for all the help.

 

[Nige]

For what it costs I would replace the bolt-on brace with a new one, or have one made up - it can't be that complicated. That being the case that it's not the integral brace close to the flange where your crack is that's broken I would be quite happy if I could find someone with a MIG welder who I'm sure could do a nice repair job on the crack between the tube and the flange. BTW, don't forget to replace the O-ring #14 when you refit the oil suction tube.

Here are the other 2 valves that you mentioned. The one on the oil filter body (#10 & 11) is the bypass valve in case the filter element plugs. Not sure what the one (#6 & 7) on the oil pump housing does, maybe one of our excavator experts can enlighten us.

 

[Logan]

Thanks Nige, I'm wondering what kind of steel they were using for the brace. It has been repaired in several places and has a crack developing near a bolt hole at the bottom too.It looks like maybe zinc coated steel but is behaving like high tensile with the cracking. I'm considering using mild steel flat bar in the same size and just sanding all the black casing off it, then using triangle braces on the bent right angle sections of the brace to make it stronger. This machine has been in logging all its life -20 odd thousand hours, so obviously the standard brace can't handle the rigours put to it. I have a good MIG so I'll get into it while the valves are being sourced and in transit.

 

[Nige]

Generally something like that is nothing more than mild steel. Don't try to make it too strong otherwise you run the risk of something else breaking.

 

[Logan]

Thanks Nige. What's the deal with sump stud torque, do they have a setting? I noticed some were loose and some tight so will use thread locker on them as well as a torque wrench, my new favourite toy.

 

[Nige]

Thanks Nige. What's the deal with sump stud torque, do they have a setting?
.

not afaik, but I can't check right at this moment.

 

[Logan]

As promised heres a pic of the old girl back in action shovelling pinus radiata for export.

 

[Nige]

All good now I take it ...??

 

[Logan]

Yep all good thanks Nige, she starts easy and runs well. A big thank you to everyone for all the help and support. Much appreciated. Cat said torque the sump bolts to 15-21nm. Can anybody recommend a source for service manuals for a Cat 320L 9kk model? Just after a digital version not the $1400 version from the meow dealers.

 

[Nige]

There are no digital versions unfortunately unless you buy the subscription to SIS-web. If you thought parts prices were steep the cost of the annual subscription will make your eyes water. eBay would be your best bet. Manuals come up there from time to time but you can still expect to pay a fair chunk of money for one.