We have this ex 374D with 8075hrs presently, Engine oil started leaking from the starter motor after 6500hrs. We suspected the crankshaft oil seal but after loosing we found there was no crankshaft oil seal but oil from the flywheel housing is not returning to the sump. So the housing get filled then oil will start coming out from the starter motor area. We changed the engine oil pump but still the same result. Can someone help me with the solution. Thanks
Not sure on this but make sure your engine isn't a wet housing type. The oil maybe normal and you may just have a seal failure on the starter motor. Someone should chime in with more knowledge on this engine soon.
Thanks for your respond but I don't think it's normal because we have been using the same machine for long before it started leaking oil from the starter motor and we have changed the starter motor seal but the same result. When I opened the flywheel housing drain plug 4 to 5 litres of oil flows out. I believe those oil suppose to return to the sump through the return line but the oil flows out from the starter motor area.
Serial number would help
I'm not familiar with the model number EX374D. Is that a Hitachi? What is the make and model of the engine? Does this machine have a gear drive to run multiple pumps or just a single pump set? You will need to provide more information.
The make is Caterpillar, model is 374D powered by C15 engine. Single pump. Serial number is PAS00791.
Serial number: PAS00791
Problem is inside starter
I know the big Cat excavators went to a spring type damper on the flywheel but haven't heard that engine oil was supposed to enter the case and drain back to the engine. Can someone confirm this type of set up?
In cat ex 374D there is a provision for oil that entered the flywheel housing to go back to the sump not engine.
I'm thinking that when John wrote "drain back to the engine" he was meaning that the oil would drain back to the engine oil pan, what you refer to as the sump.
Ok. Thanks
Could problem be overfilling of engine? Or a restriction in the drain from flywheel housing, be it a hose or what ever? One somewhat off the wall question, does this engine have a prelube pump mounted on it?
John C is right with the setup
Which set up are u talking about? I need someone to give me idea on what to do in order to stop the leakage.
Is the bell housing fill up with fluid?
The housing is not fill with oil.
The housing is not fill with oil.
Again I think language is a problem. John's not asking if the housing is supposed to be filled with oil, he's asking whether if you start with it empty it actually fills up with oil while the machine is working, and eventually the oil level in the bell housing gets so high the oil starts to come out of the starter motor..?
I spent some time on SIS and could not find anything that said flat out what if anything was suppose to keep oil from getting into the housing. I did see mention of a rear seal but that was just for a basic engine and there was a line there that said not all engines have a rear seal! I guess I need to go back there and copy and past that line here.
@Nige , that is exactly what is happening.
Not clear on this machine having not seen on in person either assembled or apart. Is there a drain line of some kind from the flywheel housing back to the sump/oil pan? Or is it designed to have oil drain back to the sump/oil pan from the area where the rear seal would normally be installed?
Well while I do some more digging here's a bit for thought and discussion: Note that the item I colored in red #1 is called a screen assembly. Makes me wonder if this is a suction line from the flywheel housing and they installed a screen in the tube to keep chucks from broken starter or ring gear teeth causing problem in a pump or some things else in the engine. I'm thinking that maybe a good place to start would be to remove and see if it is restricting the flow of oil out of the housing.
This is not one of the easiest machines to find information on in details where you want them. Here is what SIS shows for the oil pan and plate. I'm just guessing now that the red arrow I put on the drawing points to where elbow #7 in my last post might connect to the oil pan and the line going forwards from it is maybe connected to the scavenger side of the oil pump in the sump of the engine? I did look in SIS and the oil pump does have two separate sets of gears for this application!
One more picture showing the oil lines inside the pan. Note I colored the "screen" from the first posting of the pictures red in this one too to keep straight what we are looking at. Just one more reason I would be taking a good long look at that "screen" that looks like a pipe coming from the flywheel housing before I looked anywhere else.
I've seen the dampers used on Komatsu excavators for years but was surprised with I saw one on a Cat 345D a few years ago. In my experience the damper cases had their own oil which did not mingle with the engine or the hydraulic pump. In that case at times the rear main seal on the engine would leak and fill up the damper case and things would get hot. So hot it would burn the paint off the bell housing. The other leak that can mess things up is from the input shaft of the hydraulic pump and it will do the same thing to the paint. It was common practice to replace the rear main seal and install a speedy sleeve anytime the pump was removed. Now if Cat is mingling damper oil with engine oil, I see a very bad potential for hydraulic oil contaminating engine oil. That's a big engine with a lot of cost to be risking on that kind of design.
Anyone with access to SIS. I have been going round and round in SIS on this PAS00791 374D. For the life of me I can not find where Cat has the specifications on the engine oil pump. I finally did find the spec's for the pump but had to look under 3406C and found the 198-1508 pump spec's! One other thing I did find there is a different drawing of the line to the flywheel housing that I colored red back a few posts: In this one they clearly show the "filter" that is actually a separate part from the tube and it is the same 3T6471 part number listed for the 374D engine one. Sure looks like a wad of mesh or something similar and those lines go right to the back of the engine oil pump scavenger section.
Not what I would call an exciting piece of engineering.
There is a service lettre on the starter when hes leaks
Any chance you could scan that and post it here?
Double lip seal and boot becomes hard and brittle due to high oil temperatures in wet flywheel housings on certain 374D, 390D, 374F, and 390F Excavators. If the starter does not crank, oil may have ingressed in to the starter
I went to SIS the same picture u updated help me after some reasoning and research to solve the problem. So the problem is now solved.
Was the “screen” that ksh found on SIS actually blocked..?
Glad it helped but how about a little more details on what you found to correct the problem. This may help the next person who comes along with the same or similar problem. If it was indeed something plugging the screen what was it? I hope you did not just remove the screen as someday something like a broken ring gear tooth might it's way to there and with nothing to stop it it could damage the pump or something else in the engine!
There is no restriction in the line, the screen is very clean even when we changed the oil pump it was found okay. I Considered new oil pump and screen is okay then i concluded that the problem is from the tube, maybe it was sucking air from along the tube then I decided to check the o ring 19 from the picture and found that the o ring is bad then I changed it and tested the machine for complete 5 hrs no leakage even now the machine is working fine.
The screen is not blocked.
So it was actually a problem of lack of suction rather than something being blocked. Interesting............
Yes it was su Yes it was a suction problem.
And believe it or not but if you look under a 390F Excavator RDP1-139 there is an even better view of it - Item 1 in the illustration below. Why this illustration should be different to all the others I have no idea. Also interesting but the 3T-6471 Screen is actually a lot more common than you might think, especially in late model track-type tractors installed in the suction side (usually TC scavenge) of the Power Train oil lines. A search for the P/N threw up no less than 564 results ............. Question for the OP. There are 3 identical O-Rings (Item 14 in the illustration above) in that assembly, one on each end of the tube with the screen in it, and the third one in the vertical connector. Which one was the bad one and did you replace all three of them..?
Glade to hear the problem has been fixed. I would have thought that if the oring was bad enough to not allow the pump to clear the oil out of the flywheel housing that it would have been leaking to the outside and be very visible. Or was the bad oring on the vertical connector so any leaking from bad oring was actually an internal leak into the oil pan? Then again it would not be the first time I had seen a seal or gasket that only leaked in one direction or one that only leaked with no pressure was applied but sealed when under pressure!