Topic: Funny noise with low oil pressure

[pushin9s]

I have had my 350F for a month now and after rebuilding and setting the carbs and adjusting everything it is running very well.  I rode it about 25 miles today all on back roads at speeds between 40-50 mph except for one 1-1/2 mile jaunt down the freeway at 65-70 mph.  All day the bike did great but I noticed the last 2 stop signs before my house when I pulled the clutch in to stop the engine seemed to stumble just a might but did keep running.  As I pulled into my driveway and parked in front of the garage the oil light came on steady.  I revved it up to around 2,000 rpm and the oil light went out but then the engine started making a very high pitched squeal, kind of like a shaft chattering in a bushing (like a cheap window fan might make).  Above approximately 2200 rpm the squeal and the oil light go away but coming back down to idle the squeal comes back and the oil light comes on.  Using my large screwdriver I can hear the squeal just about any place on the engine case but it is very dominant if I listen on the right side of the crank, near the point cover. 

Have I spun an engine bearing perhaps?  And if so, are oversized bearings available now, or crankshaft repairs possible?  I tried to rebuild a 550 Nighthawk back in '87 or '88 and we had to junk the engine because the crank could not be built up and oversize bearings were not available.  Hopefully, this can be fixed.  Ideas?

EDIT: I just changed the oil and used Castrol 20W50.  The oil I drained seemed to be very, very thin and after it got warm the clutch wouldn't operate properly.  I suspect it has been run with too light weight and the wrong oil

[Deltarider]

Did the oil smell of gas?

[pushin9s]

Did the oil smell of gas?

No sir, it did not.  Just very, very thin.  And it was also very clean with no metal in it that I could see.

[pushin9s]

I had an epiphany this morning on this issue.  Yesterday morning when the bike was cold and I was trying to start it and let off the starter button the starter made that "squealing" noise and it was noticeable as the engine died about the same time.  Could I possibly have 2 separate issues going on here?  A starter sprag clutch acting up AND an oil pump going soft on me, possibly in need of some TLC and new O-rings?  Other than dismantling the engine, how can I troubleshoot further? 

[bryanj]

You do not have to strip the engine to service the oil pump juat remove the sprocket cover, as a bit of advice use an impact driver to loosen the 3 oil pump cover screws BEFORE removing the pump from the crankcase that way you are not chasing it arround the workbench trying to undo super tight screws.
The o ring under the cover is not listed in any parts book but the size has been discussed on here many times.

It is also more common for the pressure switch to play up rather than oil flow fail BUT be wary of replacements as some firms sell a car one that will fit but puts light on at a higher pressure which unecessarily worries you.

[pushin9s]

Thank you for the response Brian.  I guess what I'd like your opinion on now is "do these engines have a history of spinning bearings"?  I knew that I could service the pump on the bike, but I do appreciate the tips about loosening the bolts and I hadn't thought of dropping the pan and inspecting the pickup tube or screen.  All good ideas and I thank you for your input.  Much appreciated

[bryanj]

As the 350 never officially came to UK i have never actually seen one "in the flesh" as it were but i have worked on shall we say several 400 and never yet seen one spin bearings.

I have replaced a crank etc on a 750 where Honda had a batch of bad oil lines early on;
A full strip on a GL 1000 where the owner cross threaded the oil filter bolt and then DROVE it 5 miles with no oil to my works, then got upset when i refused to just fir a front cover!!
And i have seen ONE 500 with a worn crank but not spun bearings---this had obviously been run with very few oil/filter changes and had lots of "grit" in the cases

In conclusion I would be of the opinion that if the bearings have spun I would suggest you retire to bed for a least a year as you would be the unluckiest owner I heard of!!

All the best

Bryan

[flybox1]

EDIT: I just changed the oil and used Castrol 20W50.  The oil I drained seemed to be very, very thin and after it got warm the clutch wouldn't operate properly.  I suspect it has been run with too light weight and the wrong oil

which castrol 20/50?

non-synthetic 10w40, or 15w40 is plenty
shell rotella, belray MC oil...and plenty of others.
The wrong oil can cause the clutch issues you are having.

[pushin9s]

I don't know what oil was in it when I bought it, but it was very thin and the clutch would stop working properly when the oil got hot.  I did drain it and refilled with Castrol 15W50 motorcycle oil.  The clutch works great now but I did get the oil light yesterday.  Today I went out and started it and it made no strange noises at all and I let it run for about 5 minutes at 3,000 rpm then idled it down to 1700 rpm for a total running time of about 10 minutes.  It never made any funny noises and the oil light stayed OFF. 

I think I will order a new oil pressure switch and also an OEM oil pump rebuild kit from Charlies Place and see if that will help my oil light problem.  Sure hope it's not a bearing problem.  I started my brothers CB350 twin today and his starter made the same noise my bike was making yesterday.  So I'm thinking I may be on the right track with a starter sprag clutch giving me fits.  I'll let you know, and keep those suggestions rolling in.  I'm eager to learn.

[Deltarider]

Why would you order new parts if you don't have a proper diagnosis yet? If oil warning lamp is ON with IGN key on and extincts after start, it seems to me pressure switch is OK. If oil pomp shows no leakage, why would you open it? I cannot suppress the feeling something was wrong with that oil that you described as very thin. Are you sure fuel has not thinned the oil? Are the overflow tubes underneath the carb floatbowls all four open?

[pushin9s]

Why would you order new parts if you don't have a proper diagnosis yet? If oil warning lamp is ON with IGN key on and extincts after start, it seems to me pressure switch is OK. If oil pomp shows no leakage, why would you open it? I cannot suppress the feeling something was wrong with that oil that you described as very thin. Are you sure fuel has not thinned the oil? Are the overflow tubes underneath the carb floatbowls all four open?

Delta, the oil I drained out had no fuel smell or any other strange odor.  It was a nice brown color but wasn't black and dirty like old, neglected engine oil would look.  My suspicion after watching the clutch fade after the oil was hot and the oil pressure light coming on is that the PO just poured something in it and it wasn't made for motorcycle engines and it was too thin.  With the current 15W-50 I can turn the oil pressure light out with just a stab or two of the kickstarter when the engine is cold and now the clutch is working nicely no matter how warm the engine is or how far I've ridden.  The oil pressure light now only comes on after I've ridden it for an extended period of time and I let it idle down while I open my garage door to drive it in.  So my reasoning now (and it may be flawed) is that once the oil gets hot; A) the pressure switch may not be properly registering the pressure down at the lower spectrum of the acceptable range (5 psi?) and/or B) once the oil gets hot it is leaking around one of the O-rings in the oil pump and losing just enough pressure to trigger the oil pressure light. 

That's where I am now.  I openly admit I may be wrong and I may be chasing rabbits so I'm clearly ready to glean more wisdom from you folks.  This is one issue I've never had to deal with on the RDs. 

[Robbo]

May be a dumb question, but is the oil level correct on the dipstick?

Also, is it the correct dipstick for the bike?

Finally, if it were me, I would use that first oil change as sacrificial and only run it a few times and then replace it again.  Did you change the oil filter?  If not, do it now and inspect the inside to make sure it hasn’t blown up or spun internally.  If the wrong oil was used, who knows when the filter was last changed.

Btw, I am using Castrol 10w-40 in my 350F with no issues.



Sent from my iPhone using Tapatalk

[pushin9s]

What is the warm engine idle speed? It should be above 1,000. If you hold the idle there, does the oil light extinguish even after the motor is warm?

Yes, I keep the idle speed adjusted to 1700 rpm and it holds steady after the engine is warm and when the oil light eventually does come on, the rpm is at 1700.  I can rev it slightly up to 2000 and the oil light will go out.  The light will sometime light steady and sometimes it will blink on and off. 

And for your questions Robbo, I did not change the filter as the filter bolt head is farged all to pieces.  I ordered a new one but the vendor sent the wrong one.  The correct replacement is on its way and I'll do that next time I head to garage with it.  I have a K&N filter for it and also ordered an OEM filter from 4into1 or Charlie's Place, I don't remember which now.  I think you're correct and I'll change the oil again and inspect it for particles and also tear into the filter if I don't find anything glaring there.  With the way the filter bolt head is messed up there is a very good possibility that someone didn't properly install the filter there. 

I thank everyone for their good comments and all the good suggestions.  Also, don't know if the oil dipstick is correct, but it appears to be and it has the proper amount of oil showing on it; i.e., after putting in the second quart it still showed no oil on the stick.  After putting in the required 3.2 quarts the oil level on the stick is right at the full mark when the stick is just resting on the threads, not screwed in. 

[Deltarider]

You will not find many CB350Fs that still have the oilfilter bolt in good order. It was a poor design with that undersized head. There is a good imitation bolt on the market that you can use a 17mm wrench on. Much cheaper too. https://www.cmsnl.com/honda-cb350f-four-general-export_model14632/boltcenter-oil-non-oe_15420333000p/#.XDegcWnvJVc

[bryanj]

All the fours had that sizes bolt head to stop it being overtightened, as long as a good quality, 6 sided correct size socket is used the always undo!

[pushin9s]

The current filter bolt looks like someone tried to remove it with a rusty pipe wrench then drove an 8 point socket on it then used a 3/4" impact wrench to remove it.    The new filter bolt is on it's way and I believe I'll take Deltarider's advice and not just throw parts at it right now. I'll wait and change the filter and make sure everything is in good order inside the filter housing, then I'll change the oil again and refill with some more good mineral (dinosaur) oil of the proper viscosity and see how it does with that.  I'll be off to work for a couple of weeks so it will be a while before I can get back to it, but I'll keep everyone informed.  Again, my sincere thanks for those who have replied with all the helpful responses.  I do appreciate your time and concern.

[Deltarider]

Honda recommends a torque value of around 3 kg/m (22 lbs/ft) for that oil filter bolt. That's quite a lot for a 10mm head that's faced to the elements year in year out and doesn't stick out much to begin with. Yes, it can be done with the right socket* but you have to be fully concentrated. I always use a T-handle.
* not found in the tool bag.

[bryanj]

Dont forget that there SHOULD be a spring go on the bolt first then a washer to protect the filter rubber seal before the filter is fitted.
First thing i ordered from dave silver when i started back working on old Hondas was 10 washers and 5 springs!!