Kent Engine - Funny sound

[Hawke]

Just fitted this spare engine, and there is a funny noise. You can hear it at from the 7 second mark.

https://youtu.be/ua7WIjCaTOI


When the engine starts, its OK, but the noise starts after a couple of seconds. Gone over the engine with a stethoscope, and felt with fingers over pumps, covers, sump. Have felt the clutch bearing, and checked it before fitting the engine. Its not in gear.

I did weld up a crack on the adapter plate near the starter, but didn’t see any weld in the inside.


Any thoughts?

PS Merry Xmas to all, and to those in the North - keep warm. It looks like its a bit cool. Sunny 31 here today.

[Gordy]

If you have one, it could be the crank scraper.

[bob darcey]

The sound reminds me of the sound a fuel pump makes when operated by hand in free air. Still there when the valve cover vent is connected?

[Hawke]

The sound reminds me of the sound a fuel pump makes when operated by hand in free air. Still there when the valve cover vent is connected?

Bob, still there with the valve cover vent connected, and also with the valve cover off as well.

Further investigation found that a hard brake line was just touching the gearbox adapter. As it's Xmas eve here, and people are winding down, I thought in the interests of good neighbour relations, I wont start the car up and make a racket. (I live in the inner west of Sydney. There's plenty of neighbours close by. I'll give it another go after the festivities have died down.

[Hawke]

If you have one, it could be the crank scraper.

Could be. While it was several years ago when I built the engine, I did make the scraper myself. Pretty sure that I checked it when I installed it. It's entirely possible that I cocked it up.

[stonebridge20]

It's good you found the problem and can have a peaceful Christmas.

Do yourself a favor and swap out that plastic fuel filter for a metal one.

[Hawke]

It's good you found the problem and can have a peaceful Christmas.

Do yourself a favor and swap out that plastic fuel filter for a metal one.

Curious to know what’s the problem with the plastic fuel filter.

PS, I think I remember running into you at the 50th race at Road America.

[hdsporty1988]

Curious to know what’s the problem with the plastic fuel filter.

PS, I think I remember running into you at the 50th race at Road America.

The plastic filters can melt with a catastrophic result.

[DaveW]

I've had a sound similar to that when the bottom of the bellhousing was just touching the ring gear due to deformation due to running over a curb, etc.

OTOH, it also sounds somewhat like the squealing noise that a dry/seized bearing can make.

[problemchild]

OTOH, it also sounds somewhat like the squealing noise that a dry/seized bearing can make.

I think that such a bearing noise would get better or worse if run for 15-20 seconds. Fingers crossed that it is interference between parts that will harmlessly clearance themselves.

[stonebridge20]

The plastic filters can melt with a catastrophic result.

Or split in half and burn you and your car into an unrecognizable lump of char.

[Garey Guzman]

it also sounds somewhat like the squealing noise that a dry/seized bearing can make.

I immediately thought TO bearing.
Does it change with engine speed?
Does it go away when depressing clutch pedal?
With rear in the air, does it change in gear and revved?

[roadracer]

Good suggestions, especially crank scraper and/or bellhousing interference.

One thing you could try to help diagnose the issue. Remove the spark plugs, oil the bores (to help reduce friction) and slowly turn engine over with a long wrench on the front crank pulley. If you can feel any interference it might help diagnose the location. If you do feel something "hit", mark the flywheel with a chalk mark and determine if it happens on the next revolution... or half revolution.

Bets are on the crank scraper, but it will be something simple. It always is!
Good luck with this!

[Hawke]

I immediately thought TO bearing.
Does it change with engine speed?
Does it go away when depressing clutch pedal?
With rear in the air, does it change in gear and revved?

There was plenty of clutch free play and I did push the clutch lever to engage the TO bearing. No change to noise.

Being Boxing Day here, and many people enjoying the holiday, I shan't be revving up the "noisy car" here in the burbs. I'll wait till Wednesday when some return to work.

[Steve Demeter]

Every spring just to make sure the brakes brake, the shifter shifts, there are no obvious problems with the engine, to make sure that the alignment is not grossly off, I take by FC for a few laps around the block in suburbia. Maybe a bit rural in our particular niche, but still within corporation limits.


The only comments I have ever had were to the tune of next time you do that stop by my house and rev it up...

[Hawke]

Fixed. Turned out to be brake hard line just touching and vibrating on gearbox lower nut. This engine is 6mm longer and 11 narrower on the left side than the previous engine.

Photo shows hard line now moved from gearbox nut, and spacer that I had to make to centre engine in frame.

[TimH]

Fixed. Turned out to be brake hard line just touching and vibrating on gearbox lower nut.

Problem solved and a potential disaster avoided. That's a win for using your ears.

[DaveW]

Fixed. Turned out to be brake hard line just touching and vibrating on gearbox lower nut. This engine is 6mm longer and 11 narrower on the left side than the previous engine.

Photo shows hard line now moved from gearbox nut, and spacer that I had to make to centre engine in frame.

If it were my car, I'd put a piece of rubber hose over the brake line at that point and let the rubber be firmly pressed/tied against the nut/gearbox. That will keep it from vibrating and maybe fatiguing in the future. If it was vibrating enough to hear, it is vibrating enough to fatigue.

[DaveW]

Fixed. Turned out to be brake hard line just touching and vibrating on gearbox lower nut. This engine is 6mm longer and 11 narrower on the left side than the previous engine.

Photo shows hard line now moved from gearbox nut, and spacer that I had to make to centre engine in frame.

If it were my car, I'd put a piece of rubber hose over the brake line at that point and let the rubber be firmly pressed/tied against the nut/gearbox. That will keep it from vibrating and maybe fatiguing in the future. If it was vibrating enough to hear, it is vibrating enough to fatigue.

Also, I assume you noticed what looks to me like a crack in the frame where you scraped off the paint.

[Hawke]

Also, I assume you noticed what looks to me like a crack in the frame where you scraped off the paint.

Dave, thanks for that. The hard line will be ultimately tied down with a cable tie. Usually to the return oil line to the pump.

Didn’t notice any crack when I pulled the engine out, but will be having a look this arvo.

[DaveW]

New word for me: arvo = afternoon

The "crack" could just be a scratch, but better safe than sorry.

[Hawke]

New word for me: arvo = afternoon

The "crack" could just be a scratch, but better safe than sorry.

Dave, it was just a scratch.

Glad to hear that you are learning to speak Oz.