Exhaust leak????????????
Thread Starter
|
Stage IV
Joined: Jul 2006
Posts: 4
Likes: 0
Exhaust leak????????????
Hi Guys , just went to go for a ride on my 94 Ultra . I have about 1000miles on it since i bought it . As I pulled out of the driveway and throttled up the street , i heard this exhaust leak type sound. It got worse very quickly. Returned home to find leak . Its not in the exhaust pipes . The leak is somewhere in the open chamber behind the spark plug where you can see across the head from one side to the other. Harley's are new to me and I know very little about them but i am heavy equipment mechanic and should be able to perform most work if i knew what is wrong . i suspect head split ???
Any of you guys experience this problem, any help would be appreciated
Thanks garry
Any of you guys experience this problem, any help would be appreciated
Thanks garry
Tourer
Joined: May 2006
Posts: 458
Likes: 5
From:
RE: Exhaust leak????????????
Are you sure it's exhaust gas leaking and not breather air? Is it oily or sooty? Put a compression gauge on it and see if one of the cylinders is lower than the other. That would indicate a leak from the combustion chamber. If compression is good, the start looking at a rocker box gasket leak.
By the way, if you don't have a factory service manual, then GET ONE NOW!! Before you start tearing into it. They only cost 50 bucks and can save you hundreds or even thousands of dollars.
By the way, if you don't have a factory service manual, then GET ONE NOW!! Before you start tearing into it. They only cost 50 bucks and can save you hundreds or even thousands of dollars.
Thread Starter
|
Stage IV
Joined: Jul 2006
Posts: 4
Likes: 0
RE: Exhaust leak????????????
Thanks for the replies guys , a few people have said it might be a rocker gasket , is the base pressureised to the point that it would sound like cracked exhauset manifold on a 350 chevy. I talked to the harley dealership today , the mechanic said he never heard of an exhaust leak coming from that location . Compression test will tell me a lot. So if i get good comp. on both cylinders , where would that exhaust leak be originating from ? like i said before it seems to be coming from that chamber in behind the spark plug.
Again thanks for any help
Garry
Again thanks for any help
Garry
Tourer
Joined: May 2006
Posts: 458
Likes: 5
From:
RE: Exhaust leak????????????
Yes, the rocker boxes are pressurized. There's a "umbrella" valve in each head to keep the breather air flowing in the correct direction. If it's leaking there, then you should be getting some oil mist or drops coming out.
If the cylinder pressure is good, then the only other place you could have an exhaust leak is where the head meets the pipe or inside the exhaust port. Bad gasket? It might just be in a location where it's blowing the exhaust into that area... although it's not likely. As I asked before.... are you SURE it's exhaust gas that is leaking? How do you know? You can't just go by a sound, you need to find a visible leak. Heck, it might just be the carb making more noise. Have you changed air cleaners lately?
If it is indeed exhaust gas, then you could have a crack in the exhaust port of the head. That should be easy to locate once you pull the head. You can probably get it welded with no problem. Does it do this when the engine is cold, hot, or both? Sometimes cracks won't leak until they expand because of the engine heating up.
If the cylinder pressure is good, then the only other place you could have an exhaust leak is where the head meets the pipe or inside the exhaust port. Bad gasket? It might just be in a location where it's blowing the exhaust into that area... although it's not likely. As I asked before.... are you SURE it's exhaust gas that is leaking? How do you know? You can't just go by a sound, you need to find a visible leak. Heck, it might just be the carb making more noise. Have you changed air cleaners lately?
If it is indeed exhaust gas, then you could have a crack in the exhaust port of the head. That should be easy to locate once you pull the head. You can probably get it welded with no problem. Does it do this when the engine is cold, hot, or both? Sometimes cracks won't leak until they expand because of the engine heating up.
Thread Starter
|
Stage IV
Joined: Jul 2006
Posts: 4
Likes: 0
RE: Exhaust leak????????????
Thanks Spect for the info .Well I done a comp test this evening . Bad news , 85psi on the back cylinder and 15 on the front.
I removed the air cleaner and discovered that theres compression coming out around the head gasket....." Blown gasket" .
But It still has the exhaust leak/sound coming from behind the spark plug . Ive been wrenching for about 45 yrs and have built many many b/b mopars so i am fairly familiar with sounds . diffinately exhaust coming out in there . sounds like a head split down the middle lol
not a very prognosis so far . can i remove the head without taking the engine out of the frame ? What would be a reasonable price to pay to have a head gasket replaced and maybe the head ?
Thanks again
I removed the air cleaner and discovered that theres compression coming out around the head gasket....." Blown gasket" .
But It still has the exhaust leak/sound coming from behind the spark plug . Ive been wrenching for about 45 yrs and have built many many b/b mopars so i am fairly familiar with sounds . diffinately exhaust coming out in there . sounds like a head split down the middle lol
not a very prognosis so far . can i remove the head without taking the engine out of the frame ? What would be a reasonable price to pay to have a head gasket replaced and maybe the head ?
Thanks again
6th Gear
Joined: Jul 2006
Posts: 14
Likes: 0
RE: Exhaust leak????????????
Yes, you can pull the head in the frame. Gonna have to pull the tanks off. The job will be 100 times easier if the motor is out of the frame, but it can be done. I blew a head gasket on my 99 Evo. I replaced em both, since I was working on it anyway. The pain in the **** part is getting the rear cylinder rocker boxes back on in the frame. I had to loosen the mount bolts and wiggle and waggle. S&S makes some nice 2 piece rocker boxes, and the umbrella valve seat is raised; so you won't get the oil on your leg Evo's are famous for. Get the manual, so you'll have all the torque values handy for your bolts.
Trending Topics
Tourer
Joined: May 2006
Posts: 458
Likes: 5
From:
RE: Exhaust leak????????????
Ouch! Blown gaskets will do it! It sounds like either both gaskets are shot, or one is shot and the other head needs new rings/honing. 85 psi is pretty low. A stock bike will have at least 125-150 psi. There still may not be anything wrong with the head. Pull it and inspect it, or have a shop do a dye-penetrant inspection for cracks. You can actually buy the inspection kit yourself for a fair price. Sometimes you have to put the head in the over at about 400 deg. for a crack to show up (expansion). You'll need new valve stem seals after that, of course.
Yes, the rear rockers can be a pain to remove (the bolts), but if you remove the top motor mount like the manual says to do, and also loosen the other mounts, you may be able to tilt the engine over to the left enough to get on the bolts. If not, then just cut the end of an allen wrench (the short end) so it's only 3/8 inch or so long. Then you can slip it under the frame onto the bolts. That's the way I've always done it on my Dynas, but I'm not positive it'll work on your bike.
You can find used heads on ebay for very low prices. I picked up a set that was already ported, including valves, springs, etc. for $400.00 last summer. Stock heads are even cheaper. No need to spend more on the S&S or other brands unless you want to start building for more power. If you want to up your compression a little, get a Cometic .030 thick head gasket set. The stock Harley rocker box and base gaskets will work fine and won't cost much. While ya got it apart, you might as well change all the gaskets (inspect the sealing surfaces carefully) and DO NOT use any gasket sealer on those gaskets!!!!! Never use it unless the factory manual calls for it. If something is leaking, then either the gasket is damaged or the parts' mating surfaces are warped/damaged/dirty.
Yes, the rear rockers can be a pain to remove (the bolts), but if you remove the top motor mount like the manual says to do, and also loosen the other mounts, you may be able to tilt the engine over to the left enough to get on the bolts. If not, then just cut the end of an allen wrench (the short end) so it's only 3/8 inch or so long. Then you can slip it under the frame onto the bolts. That's the way I've always done it on my Dynas, but I'm not positive it'll work on your bike.
You can find used heads on ebay for very low prices. I picked up a set that was already ported, including valves, springs, etc. for $400.00 last summer. Stock heads are even cheaper. No need to spend more on the S&S or other brands unless you want to start building for more power. If you want to up your compression a little, get a Cometic .030 thick head gasket set. The stock Harley rocker box and base gaskets will work fine and won't cost much. While ya got it apart, you might as well change all the gaskets (inspect the sealing surfaces carefully) and DO NOT use any gasket sealer on those gaskets!!!!! Never use it unless the factory manual calls for it. If something is leaking, then either the gasket is damaged or the parts' mating surfaces are warped/damaged/dirty.
HD Forum Stories
The Best of Harley-Davidson for Lifelong Riders
7 Surprising Harley-Davidson Products that Are Not Motorcycles
Verdad Gallardo
8 Best Harley-Davidson Motorcycles Ever
Pouria Savadkouei
10 Worst Harley-Davidson Motorcycles Ever
Pouria Savadkouei
Killer Custom's Jail Break Is The Breakout That Refused to Blend In
Verdad Gallardo
Crazy Bunderbike Build Looks Amazing, But Is It Impossible to Ride?
Verdad Gallardo
Harley-Davidson Reveals Super Cool Cafe Racer Concept
Verdad Gallardo
Engraved Rebellion: Inside Bundnerbike's Glam Rock II
Verdad Gallardo
10 Motorcycles You Should Never Buy
Joe Kucinski
10 Things Harley-Davidson Needs to Fix in 2026
Verdad Gallardo
Thread
Thread Starter
Forum
Replies
Last Post
GymChamp
General Harley Davidson Chat
10
Nov 26, 2009 02:56 PM
