2001 Trx350fm oil pump

[Awrenchturner 6]

Hello everyone,

 

I am wondering if anyone has any idea of what could have happened to this oil pump. I got this machine from a guy who said the oil pump quit. The piston was black on top and the middle piston ring is somewhat seized in the piston but all are still in tact. The crank still moves well with little side to side play. I had someone with SOME knowledge say to get a new oil pump and piston and put it back together and it should run. The scavenge inner rotor is chipped and the scavenge outer rotor has some roughness where it meets the the inner rotor. I am trying to get this machine going again and I am just wondering what may have caused this? Thanks 

[_Wilson_™ 5,859]

is this  the same bike you had posted about about  the oil drain plug being striped  out ? and you had rebuilt the top end ??

Edited August 15, 2020 by SlammedRanger

[87Iroc 339]

My vote would be run without oil. 

[jeepwm69 6,581]

I'd check that crank very carefully.  I have yet to rebuild a single 350 Rancher motor that didn't need a crank.  The wristpin to connecting rod fit gets loose and you'll never get it to stop smoking without replacing the crank.

 

I've seen someone who had an oil pump seize when a needle bearing roller found it's way into the pump.

 

"Got a friends 350 that just had a single roller from a small needle bearing find it's way in the oil pump and locked the pump up and broke the drive teeth on the balance shaft. Figured out if was from a starter replacement a while back when the snout of the starter broke off in the rear crankcase cover and the small needle bearing must've left a roller in the bottom of the motor. If you've done a starter recently that broke, check the needle bearing in the snout of the starter because the oil pump will draw it up the suction tube!"

[shadetree 5,429]

oil filter installed backwards would be my guess.

[Fishfiles 17,031]

Ouch , that oil pump is messed up >  would think everything is messed up , but Honda are tuff 

[Awrenchturner 6]

23 hours ago, _Wilson_™ said:

is this  the same bike you had posted about about  the oil drain plug being striped  out ? and you had rebuilt the top end ??

Hi,

 

it is another bike, my parts bike. I am thinking about getting it going. Just wondering if it is worth it or not. As for my bike, I just deepened the drain threads with a tap and found a longer M12 plug. So far it holds. I will be rebuilding it over winter, so far I ordered a flywheel puller. I was just going to take this one apart for practice and won’t feel too bad if I mess something up. However, it’s a bit of a jigsaw puzzle as the previous owner sold it to me in pieces. I am missing at least a few bolts from the oil pump and front cover which were both off when I got it. I did get a used oil pump from eBay to see if it will run, I just don’t want to put in top end work and then have the oil pump fail again to redo it all. Hopefully, there are no metal pieces as jeepwm69 mentioned flowing  around in the oil which is the first thing that came to my mind when I saw what was left of the oil pump. And, hopefully Shadetree’s guess of the backward oil filter or 87Iroc’s vote of run without oil, or even both are the culprit. Previous owner didn’t say much about it. Just said “the oil pump seized” or something along those lines. At this point, with my experience, fishflies could be right when he said everything could be messed up lol. I guess I won’t know until the rebuild(s). But I also like when he said “Honda are tough”, and this is the reason I think the rebuild(s) can wait for winter at least. What do you all think? 

[_Wilson_™ 5,859]

oh okay, i gotcha on the other bike, i was looking at the history of your post... which sometimes helps :-) i would go along with jeep, shadetree... or iroc.. was the guy you got this from a friend, or mechanic ? 

[_Wilson_™ 5,859]

another idea....that it had been sunk one time.... then the engine  taken apart flushed, then went to you hands (sold to you in pieces) but as you say the guy didnt tell you much... can you post us some more pictures of the rest of the guts that show abrassion, or any gritty residue ? 

[Fishfiles 17,031]

I would have to think that engine was run low or totally out of oil for that oil pump to gawl up like that , but then I may be wrong and something let go inside the engine and went thru it ------  one place   I would expect  you will see damage will be the connecting rod / crank , which if there is any play  left unrepaired will cause the piston to wobble and wear  a fresh  bore egg shaped quick and a new top end will not last long ----- as far as your missing bolts , on PSN or E-Bay you will find hardware lots for about $25-30 , when they dismantle the bikes all the bolts and hardware go in a pile , good source for bolts ---- you  never showed a pic of the screen , would think something had to show up there ---- anything is rebuildable , just depends how much you want to spend  

 

 

[_Wilson_™ 5,859]

i would get shades advise on this deal... he's rebuilt several utilty Honda's .... just depends on what you wish / can afford to spend ... plus ..this is a honda!keep is updated. 

[Fishfiles 17,031]

On 8/15/2020 at 8:14 AM, _Wilson_™ said:

i would get shades advise on this deal... he's rebuilt several utilty Honda's .... just depends on what you wish / can afford to spend ... plus ..this is a honda!keep is updated. 

I would too 

[_Wilson_™ 5,859]

nah... i don't think so.... but anyways lets not go off the rails.... lol!

[Awrenchturner 6]

Lots of fun lol,

 

Just an update for today with a few pictures. My original plan was to just put everything in/on the engine back together and fire it up just to see if it would run. And I might still do this.

However, I looked further into the engine today and found the screen is done, a twisted off bolt from the oil pipe bracket (which I drilled through so far). More... scarring on the connecting rod where the wrist pin sits aaand... two small pieces that came with the hardware pile that I need help identifying (if they even came from this bike). 

 

I am still waiting on my tools to get inside the case to arrive, so this is what I can tell you and show you at this point. Thoughts? Oh, and thanks for everyone’s input, it’s all considered and appreciated. You guys are awesome!

[shadetree 5,429]

dang bro...i hate to tell you this...but....that engine needs to be split, gone through, cleaned/flushed out really well, a new crank, and lord knows what all else parts it will need ?. i have no idea what those two parts are ?, but they sure look like something broke loose inside that engine if they came from it ?. but i do not recall what it would be from ?, like you said...it may not have came out of this engine ??.

[Awrenchturner 6]

Lol,

 

no worries, was wondering why you deem this crank no good?

[oh400ex 629]

13 minutes ago, Awrenchturner said:

Lol,

 

no worries, was wondering why you deem this crank no good?

 

You'll get your real answer from shade shortly but if the crank underwent enough stress to cause side to side play it will likely be untrue.

 

One of the reasons anyway for why you need to split the case is the loose metal in the bottom end will cause issues down the line.

 

Shade has likely taken the risk before and had to do all the work you are going to do twice. I think he is trying to save you the headache of putting it back together without going a bit deeper first. Potentially, a month down the line you are right back where you are with now more damage to the case or another component that you could save if you split the cases and do a full rebuild on the engine right now.

 

Crank can be checked with a micrometer before being replaced and you may not even need to but IMO you need to split the cases.

It's not as bad as it may seem and you will know the work is done correctly when you are finished.

From looking at your posts it's going to be no problem just a bit more time.

 

oh400ex

Edited August 17, 2020 by oh400ex

[shadetree 5,429]

27 minutes ago, Awrenchturner said:

Lol,

 

no worries, was wondering why you deem this crank no good?

i'll tell you why..from looking at the scoring on that wrist pin and the top of the connecting rod ?, this tells me the crank ran without oil ( which all of us can clearly tell from the pics ), which means it under went a great deal of heat and stress. seeing the damage so far...there is no way your going to get by putting it back together without splitting cases, replacing crank?rod ?, without it going down in a short time. oh400ex is correct, in my 29 yrs of doing atv repair, i have been down that '' i just wanna ride now '' thinking, and skip all the paying money and time for new parts, its your atv, your time, your money !, but if you come here asking for help, and do not want to listen to great, CORRECT ADVISE ?, well then, you are wasting your's and ours time. do it right, or don't do it at all.

[87Iroc 339]

With as bad as the oil pump was...it ran w/o oil for quite a while(although I bet it sucked up a piece of screen which may have caused some of the heat). I don't really think a filter in backwards would cause the pump to do that, as it would still have oil going through it and spitting out pressure relief. I think it flat ran w/o any oil in the sump.

 

What the ! caused the screen to do that, man, I have no idea. I can't even fathom. 

 

I'd be looking for a used crank on ebay. I had good luck getting mine rebuilt by Vince.... I also put a dial indicator on the output shaft of mine to see if it was bent or not. I got like 0.001" of runout on the tail for your reference.

 

If your ransmission is like the one on my 450. It almost looks like chunks shift dogs that may have sheered off when a bearing seized or maybe just from the heat. 

 

Good luck,

Edited August 17, 2020 by 87Iroc

[jeepwm69 6,581]

I would tear that thing all the way down, send the crank to Vince at Mr Crankshaft, and put it back together, replacing what doesn't look right.

 

I've rebuilt 3 350 engines in the last 2 years.  Every one of them has needed a crank.  Two of them I though would be ok, and I had to tear the engine back down again to replace the crank.

 

Do the crank, timing chain, seals, oil pump, and top end.  Clean the crap out of everything while you're in there.  You'll know what you have, and you'll know it's good.

 

Try Powersportsnation.com for parts.  Not as cheap as they used to be, but they stand behind the used parts they sell.

 

[Awrenchturner 6]

Awesome,

 

thanks Oh, thanks Iroc, thanks Shade, thanks Jeep. A year later and I am ready to do this right. I split the cases and this is what I found. I believe the two metal shards that jammed the oil pump came off the balancer, and the shift drum is also broken off on one (the rear) side. Where the shift drum was broken off there is a needle bearing. Was wondering if that bearing and all others would be ok and what to look for. I contacted MrCrankshaft and he said to send it to him for rebuild. Anyway, thanks again.

[jeepwm69 6,581]

I'd knock that bearing out that supports the end of the shift drum that broke off.  The later upgraded shift drum is thicker there and doesn't sit in a bearing. 

 

You can see here the newer style shift drum which is thicker on the end support.  00 and some 01's were the weak design.  Anything from 02-06 should be the newer design.

 

All the rest of the transmission bits are the same, so you can either just get the updated shift drum, or get a whole used transmission from a newer model.

When I rebuilt my spare 350 engine (from an 00) I got the whole used transmission cheaper than I could find just the shift drum. 

 

On other bearings, I clean them out and spin them, the oil them and spin them.  I have rarely had to replace bearings in the case, but if they don't spin completely smoothly or they have any play in them, replace them.

 

[jeepwm69 6,581]

2 minutes ago, jeepwm69 said:

I'd knock that bearing out that supports the end of the shift drum that broke off.  The later upgraded shift drum is thicker there and doesn't sit in a bearing. 

 

You can see here the newer style shift drum which is thicker on the end support.  00 and some 01's were the weak design.  Anything from 02-06 should be the newer design.

 

All the rest of the transmission bits are the same, so you can either just get the updated shift drum, or get a whole used transmission from a newer model.

When I rebuilt my spare 350 engine (from an 00) I got the whole used transmission cheaper than I could find just the shift drum. 

 

On other bearings, I clean them out and spin them, the oil them and spin them.  I have rarely had to replace bearings in the case, but if they don't spin completely smoothly or they have any play in them, replace them.

 

 

Here's one cheap on ebay.  https://www.ebay.com/itm/164644950927?epid=1444151049&hash=item26559a938f:g:dQsAAOSwDyhgAKHO

[Awrenchturner 6]

Well, I ordered that transmission you recommended. I also shipped the crankshaft to MrCrankshaft and ordered a crankshaft balancer off of eBay. I am cleaning the case up and making sure I have the parts to get the engine back together. Should I replace any seals or o-rings while I am in here? Thanks.

[jeepwm69 6,581]

Absolutely.  Seals are cheap and easy to replace with the engine out.  They're a PITA to install with the engine installed, so I always replace when the engine is out.

 

I use Rocky Mountain ATV, but find the partzilla website easier to navigate when looking for part numbers.

 

Replace the timing chain while you're in there.

 

https://www.partzilla.com/catalog/honda/atv/2005/trx350fm-a-fourtrax-rancher-4x4/cam-chain

 

Crank seal (under the pull start cage) and reverse seal (18 and 19)

 

https://www.partzilla.com/catalog/honda/atv/2005/trx350fm-a-fourtrax-rancher-4x4/rear-crankcase-cover

 

rear output seal (#9)

 

https://www.partzilla.com/catalog/honda/atv/2005/trx350fm-a-fourtrax-rancher-4x4/final-shaft

 

Front output seal #18

https://www.partzilla.com/catalog/honda/atv/2005/trx350fm-a-fourtrax-rancher-4x4/front-crankcase-cover-tm-fm

 

Shifter seal (#21)

 

https://www.partzilla.com/catalog/honda/atv/2005/trx350fm-a-fourtrax-rancher-4x4/gearshift-fork