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TOPIC: valve noise on bearcat

valve noise on bearcat 6 years 3 months ago #58620

  • schill
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Hi,
I'm wondering if noisy valves are harmful for my engine. It runs fine but seems to have more noise then I think it should. I have never adjusted the valves.
Thanks Steve

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Re:valve noise on bearcat 6 years 3 months ago #58650

  • 4stroke
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If you've never checked the clearances and think it's noisey, I'd be pulling the valve cover and checking. If the clearances are fine you'll have an idea what it should sound like.

Dick

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Dick Johnson

1989 16ft Sylvan

'57 Evinrude 18 (finally found a decent one)
'58 Johnson 5.5
'72 Johnson 6.0
'61 Homelite
'64 Johnson 18
'65 Homelite 55
'66 Homelite 55
'68 Bearcat 55 (3)
'70 Bearcat 55 (2)
'71 Bearcat 85 (Sold)

Re:valve noise on bearcat 6 years 3 months ago #58654

Just a reminder, the engine has to be cold when you set valve clearance.

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Re:valve noise on bearcat 6 years 3 months ago #58662

  • billr
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Steve,
Good question.
Dick and Craig are right on this.
You should hear some valve noise, that is the lash being taken up.
Whether it is too much or not, Dick is correct, you have to check.
In general, too much lash is better than none as the fear is that the valves receded into the head, then with no lash you risk burning an exhaust valve or worse. However, you will see a nice improvement in idle quality if you set them to factory specs given that your timing, compression, carbs are all set to factory spec too. And the factory stated the valve clearance be checked every 250 hours after break-in period service. It makes a big difference and you don't have to do it often!
It is an easy afternoon project to check the lash, the procedure is outlined in the factory service manual. I have all the shims in stock too if you need some, and factory literature too.

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Re:valve noise on bearcat 6 years 3 months ago #58749

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Thank you Dick ,Craig and Bill for your response. I will take your advise and check the clearances. Hopefully I won't break the valve cover gasket. Maybe I should buy one first.

Thanks Steve

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Re:valve noise on bearcat 6 years 3 months ago #58778

I re shimmed my Homelite and it still sounded like a Singer sewing machine. I guess they call those bucket lifter and shims.
Bill R has all the shims you need. He will even give you trade in price on your old shims that you don't need. :P
Attachments:

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Re:valve noise on bearcat 6 years 3 months ago #58787

No prob, Schill. It's always good to have an extra valve cover gasket when you need one. Actually, it's a good idea to have as many gaskets for the whole engine! Just my luck, when I want to take the boat and I need a gasket to fix something, that would be the gasket I DON'T have.

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Re:valve noise on bearcat 4 years 4 weeks ago #96210

I have one motor that runs like a sewingmachine, it's incredibly quiet despite the fact it has the early hood and no insulation.
My other 1966 homelite however is awfully noisy and I'm almost certain it's the valves. But the thing is, valve clearance is within the factory specified tolerances. Compression is ok on all four cylinders and performance is fine.
I would appreciate your opinion. Should I try to reshim with tighter clearances or is this block ready for overhaul?

Regards,
Christiaan

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Re:valve noise on bearcat 4 years 4 weeks ago #96271

  • billr
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I would not deviate from the factory valve clearances if it were me.

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Re:valve noise on bearcat 4 years 4 weeks ago #96273

  • 4stroke
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billr wrote:

I would not deviate from the factory valve clearances if it were me.


Agreed, when hot everything grows larger, the cam diameter becomes larger, the bucket/shim become thicker, the valve stem longer. The clearances then become tighter. I would use a stethoscope and try to pin point the source. Over the years I have seen valve guides worn to the point of making noise, if it sounds like just one is the source check the fuel pump and make sure the spring is in it keeping full time contact with the camshaft.

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Dick Johnson

1989 16ft Sylvan

'57 Evinrude 18 (finally found a decent one)
'58 Johnson 5.5
'72 Johnson 6.0
'61 Homelite
'64 Johnson 18
'65 Homelite 55
'66 Homelite 55
'68 Bearcat 55 (3)
'70 Bearcat 55 (2)
'71 Bearcat 85 (Sold)

Re:valve noise on bearcat 4 years 3 weeks ago #96689

It's definitely not the valve clearance or fuel pump.
Could this rattling noise alse be related to worn main bearings?
I haven't read anything about worn main bearing on the forum though.

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Re:valve noise on bearcat 4 years 2 weeks ago #96698

  • billr
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could be main bearings or rod bearings tower shaft bushings.
could even be motor mounts.
could be the distributor too I've seen that several times, bearings and or sloppy fit of drive key or home made drive key.
what oil you running? oil filter?
What rpm is the noise occuring at?
I've seen a couple engines rebuilt with used bearings that were noisy, using 50w oil quieted it down, but that is merely coping with the problem not solving it. Matter of fact the guy that rebuilt them told the customers to use 50w or 20w-50 Valvoline.
Bottom line is if you don't pull the engine out of service and dismantle it to check clearances I don't know that you can do anything but try heavier oil to see if it quiets the noise.

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Re:valve noise on bearcat 4 years 2 weeks ago #96720

Thanks for your reply Bill, I already increased oil viscosity to
15-40w.
Noise is especially audible with low RPM's. Engine sounds reasonably smooth at 2000-2500 rpm. at 5000 rpm the engine just sounds loud and raw. I have used the same oil filter for the last two years and did not replace with oil renewal as I cannot purchase this filter in europe.
I changed the distributor but this had no effect. I have a sloppy fitting metal homemade drive key and will shoot you a mail for a new one, this might be one of the sources.
Reason why I suspect main bearings is that turning the flywheel back and forth feels more sloppy compared to the other motor. I guess I will have to open the case, in order to know.
Are the main bearings made from alluminium/copper, so you can actually see when they are worn?

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