!! Need some help diagnosing an engine sound
Thread Starter
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Stage II
Joined: Feb 2014
Posts: 2
Likes: 0
From: Phoenix, AZ
!! Need some help diagnosing an engine sound
Hey, I'm new to the forums but I need some serious help/advice. I have a 98' Road Glide with 70,000 miles on it. I bought it used. Sounded and rode great. It had some engine work done to it. At the time, the cylinders had been bored once, it has a Mikuni HSR Carb, an Andrews EV13 Cam and High compression pistons.
I took it out the second weekend I had owned it on a 200+ mile ride. When we got to where we were going, I didn't notice any unusual noises or power loss but when we got back to the apartment, I could hear a surging whirring/knocking noise coming from the cylinder area. I used the screw driver trick to find out where it was coming from and it was definitely coming from the top end. I also inspected the oil tank and found that it wasn't reading any oil but the next day we checked again and the oil had made its way back. We decided to remove the engine piece by piece and there were large scrapes in the cylinders, front and rear. Also found that the oil pump had been jammed by a plastic piece that had gotten wedged in the gears in the pump.
Long story short, I bought new cylinders and pistons, but decided to go with a more flat headed piston, replaced all of the gaskets, and cleaned out entire engine to make sure there wasn't any debris left from the scraping. We reassembled the engine correctly according to the manual.
Well, I fire it up and we let it run a while so we could re adjust the timing and to re tune the carb and the exact same sound has returned. Pissed me off. I didn't even go into the timing because I don't want to run the engine. I have no idea what's causing it. I am afraid of running it at all because I'm already down on money and I don't feel like buying another set of cylinders..
The noise sounds exactly like this.
Any Ideas?
I took it out the second weekend I had owned it on a 200+ mile ride. When we got to where we were going, I didn't notice any unusual noises or power loss but when we got back to the apartment, I could hear a surging whirring/knocking noise coming from the cylinder area. I used the screw driver trick to find out where it was coming from and it was definitely coming from the top end. I also inspected the oil tank and found that it wasn't reading any oil but the next day we checked again and the oil had made its way back. We decided to remove the engine piece by piece and there were large scrapes in the cylinders, front and rear. Also found that the oil pump had been jammed by a plastic piece that had gotten wedged in the gears in the pump.
Long story short, I bought new cylinders and pistons, but decided to go with a more flat headed piston, replaced all of the gaskets, and cleaned out entire engine to make sure there wasn't any debris left from the scraping. We reassembled the engine correctly according to the manual.
Well, I fire it up and we let it run a while so we could re adjust the timing and to re tune the carb and the exact same sound has returned. Pissed me off. I didn't even go into the timing because I don't want to run the engine. I have no idea what's causing it. I am afraid of running it at all because I'm already down on money and I don't feel like buying another set of cylinders..
The noise sounds exactly like this.
Any Ideas?
Seasoned HDF Member
Joined: Dec 2010
Posts: 7,736
Likes: 1,524
From: Coromandel Peninsula New Zealand
First thing I would check is the compensator sprocket nut on the end of the crankshaft behind the primary cover.
If it isn't that and the primary chain isn't too slack (or tight)I would think it might be a main bearing as they tend to sound like a train on rails.
Hard to tell from the other side of the planet but that's where I would start.
If it isn't that and the primary chain isn't too slack (or tight)I would think it might be a main bearing as they tend to sound like a train on rails.
Hard to tell from the other side of the planet but that's where I would start.
Seasoned HDF Member
Joined: Aug 2008
Posts: 5,077
Likes: 2,137
From: Ohio
You lost oil pressure on your previous failure by the oil pump being jammed and said the same noise present, was the oil pump drive key installed properly? it can be a bastard. Pressure valve and spring checked in the oil pump?
Make sure you have oil pressure first is a must, low or no oil pressure won't pump up the lifters and sound like hell on a Evo, lifters not pumping up will cause the push tubes to be loose in the rocker arms and the noise is top side. If you did put a oil pump or clean it, they can get a pocket of air in it and not pump oil so can be a issue, takes oil priming to get it to pump.
Trying to bounce some items off you by your reported failures.
Welcome to the Evo section, hopefully we can turn this into a positive experiance on your first post
Make sure you have oil pressure first is a must, low or no oil pressure won't pump up the lifters and sound like hell on a Evo, lifters not pumping up will cause the push tubes to be loose in the rocker arms and the noise is top side. If you did put a oil pump or clean it, they can get a pocket of air in it and not pump oil so can be a issue, takes oil priming to get it to pump.
Trying to bounce some items off you by your reported failures.
Welcome to the Evo section, hopefully we can turn this into a positive experiance on your first post
Last edited by 1997bagger; Feb 9, 2014 at 08:53 AM.
Seasoned HDF Member
Joined: May 2008
Posts: 21,095
Likes: 12,638
From: South Carolina
Did you check the keys in the oil pump?
Oil pump primed and making pressure?
If you have one piece (oem) pushrods; did you reinstall the rocker supports exactly as the service manual says (piston at top of compression stroke, wait for lifters to bleed down before rotating crankshaft)?
Before you consider opening up the engine again, follow Spanners advice; check the primary chain and compensator nut.
Oil pump primed and making pressure?
If you have one piece (oem) pushrods; did you reinstall the rocker supports exactly as the service manual says (piston at top of compression stroke, wait for lifters to bleed down before rotating crankshaft)?
Before you consider opening up the engine again, follow Spanners advice; check the primary chain and compensator nut.
Thread Starter
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Stage II
Joined: Feb 2014
Posts: 2
Likes: 0
From: Phoenix, AZ
Oil pump was fine after i found the plastic thing jammed in the gear. It didn't cause any damage after i inspected it pretty good. It was a bitch getting those little half moon bastards on but they we put on correct. I replaced the oil lines and put them back in the right order. The engine is getting pressure. We followed the manual to a T and reassembled it completely. I'll reinspect the primary chain. If its too tight, what damage could it cause? it would be mainly to the sprockets or the main bearing in the hub. I'm just not sure how it would affect the pistons. I asked on a different thread and some are saying it could be a blown connecting trod bearing. But when it was disassembled, there was no travel in the rods up or down. My crank is off or my timing is really messed up.
Seasoned HDF Member
Joined: Dec 2010
Posts: 7,736
Likes: 1,524
From: Coromandel Peninsula New Zealand
Oil pump was fine after i found the plastic thing jammed in the gear. It didn't cause any damage after i inspected it pretty good. It was a bitch getting those little half moon bastards on but they we put on correct. I replaced the oil lines and put them back in the right order. The engine is getting pressure. We followed the manual to a T and reassembled it completely. I'll reinspect the primary chain. If its too tight, what damage could it cause? it would be mainly to the sprockets or the main bearing in the hub. I'm just not sure how it would affect the pistons. I asked on a different thread and some are saying it could be a blown connecting trod bearing. But when it was disassembled, there was no travel in the rods up or down. My crank is off or my timing is really messed up.
The noise might not be the pistons......
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Seasoned HDF Member
Joined: May 2008
Posts: 21,095
Likes: 12,638
From: South Carolina
Remove the outer primary cover, check the primary chain tension, and check the torque on the compensator nut.
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Seasoned HDF Member
Joined: Aug 2008
Posts: 5,077
Likes: 2,137
From: Ohio
Connecting rod bearing will make the loudest noise on a no load situation, when giving it throttle it will quiet down from load, when you let the engine back down, the crank pulling the rod back down quiets the noise plus the sound will amplify into the fuel tank.
Another clue to a rod bearing failure is the old cylinders will be scored on only one side because the drag of the connecting rod will put more force on the outer side of the cylinders. If you do have a rod failure in progress, it will score your cylinders again.
I know this failure first hand and made one hell of a mess but didn't catch it on the origional cylinder failure, just scored them. The lower bearing noise came (rapping) in shortly after a rebore and lower bearing came loose but the cylinder knock and bearing rap was 2 different sounds.
Follow advice and check the compensator nut first, it makes a horrible sound when loose
Another clue to a rod bearing failure is the old cylinders will be scored on only one side because the drag of the connecting rod will put more force on the outer side of the cylinders. If you do have a rod failure in progress, it will score your cylinders again.
I know this failure first hand and made one hell of a mess but didn't catch it on the origional cylinder failure, just scored them. The lower bearing noise came (rapping) in shortly after a rebore and lower bearing came loose but the cylinder knock and bearing rap was 2 different sounds.
Follow advice and check the compensator nut first, it makes a horrible sound when loose
Last edited by 1997bagger; Feb 9, 2014 at 07:56 PM.
