Blown head gasket
Road Warrior
Joined: Sep 2006
Posts: 1,826
Likes: 87
From: Cookson, Ok
Speaking from experience, by the time you get done with this repair you will fully understand why EVO's need proper warm-up time and you will stick to it. Your new manual will most likely tell you to remove some of the motor mounts to let the engine drop down in the front to provide more room for pulling the rear rocker box.
Outstanding HDF Member
Joined: Nov 2010
Posts: 2,627
Likes: 3
From: S.E. Va
Yes, with the rocker box gaskets make sure they don't cover the oil passages you may have to modify them slightly.
Elite HDF Member
Joined: Sep 2007
Posts: 4,468
Likes: 12
From: Bluffton, South Carolina
Digger,
Get yourself a good topend gasket set and pull both cylinders and replace all gaskets while you have it apart. Rings are optional, mostly depending on mileage and comression. The most often causes of a blown head gaskets are , not letting the engine warm up(EVO Cylinders grow about.040" when they get warm), a stud pulling out (you will need to do some case repair), or improper assembly (not enough torque).
If the engine has near 30,000 miles or more it would benefit from new rings, hone job, and valves re-seated. We see about 8-10 bikes a year wit a blown head gasket, most often the head bolt has backed out. You need to measure how much stud is sticking out of the case, they should all be the same. The length can be found in your service manual and there are different types. The ones we prefer are the ones with the redge on the bottom as that allows the stud to seat against the block.
If you take the top end off and do the above properly the engine should give you years of maintenance free enjoyment. The reason we replace both is that way we know that both head gaskets are the same thickness and both cylinders will have the same compression ratio. Even though the difference is slight it can increase vibrations and engine wear. Hope this helps, please feel free to contact us with any questions you might have as we are here to help.
Get yourself a good topend gasket set and pull both cylinders and replace all gaskets while you have it apart. Rings are optional, mostly depending on mileage and comression. The most often causes of a blown head gaskets are , not letting the engine warm up(EVO Cylinders grow about.040" when they get warm), a stud pulling out (you will need to do some case repair), or improper assembly (not enough torque).
If the engine has near 30,000 miles or more it would benefit from new rings, hone job, and valves re-seated. We see about 8-10 bikes a year wit a blown head gasket, most often the head bolt has backed out. You need to measure how much stud is sticking out of the case, they should all be the same. The length can be found in your service manual and there are different types. The ones we prefer are the ones with the redge on the bottom as that allows the stud to seat against the block.
If you take the top end off and do the above properly the engine should give you years of maintenance free enjoyment. The reason we replace both is that way we know that both head gaskets are the same thickness and both cylinders will have the same compression ratio. Even though the difference is slight it can increase vibrations and engine wear. Hope this helps, please feel free to contact us with any questions you might have as we are here to help.
Road Warrior
Joined: Jun 2009
Posts: 1,687
Likes: 9
From: SoCal & West TN
The gaskets on the Rocker Box Tops were originally Cork and a "One Time Use" only. They were replaced with the reusable ones. But don't reuse over a couple of times. And check them every time. If it looks questionable, replace it.
One big problem that all EVO motors have is the Rocker Box Top is prone to leaks. When you have the top off, take the center "D" ring off and place on a flat surface. Look to see if there is any part that is not touching the surface. Check to see if it will "Rock" when place flat. If it is not flat, replace the "D" ring. If you don't, you will never get it to stop leaking oil.
One big problem that all EVO motors have is the Rocker Box Top is prone to leaks. When you have the top off, take the center "D" ring off and place on a flat surface. Look to see if there is any part that is not touching the surface. Check to see if it will "Rock" when place flat. If it is not flat, replace the "D" ring. If you don't, you will never get it to stop leaking oil.
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Road Captain
Joined: May 2011
Posts: 684
Likes: 9
From: Indian Head, PA
I finally got to spend a little time in the garage. I got the tank all the way off, as well as the horn/bracket and air filter. I found a K&N filter that is black as black can be, probably need a new one as the mesh is a little deformed and twisted and it looks like a serious cleaning might not even be enough.
A previous person working on it drilled an access hole through the frame plates allowing easy access to the left rear rocker box screw without a cut down allen. That should help a little.
I also discovered an S&S carb. The intake manifold/Y has S&S 367 molded into it, the carb itself has S&S Shorty embossed on it and the air cleaner says S&S 380. It looks like 4 bolts(2 per side) to release the manifold from the heads, and 2 bolts(one per side) to release the carb bracket from the heads, then the only thing left is a breather and the throttle cables. I figured just hang the carb out of the way on the crash bars so I don't have to mess with the cables...
Too hot right now, I need to wait until it cools down later this evening! It would figure a giant ride rolled past my house with 100+ riders in it. I want this thing FIXED!!! LOL!
A previous person working on it drilled an access hole through the frame plates allowing easy access to the left rear rocker box screw without a cut down allen. That should help a little.
I also discovered an S&S carb. The intake manifold/Y has S&S 367 molded into it, the carb itself has S&S Shorty embossed on it and the air cleaner says S&S 380. It looks like 4 bolts(2 per side) to release the manifold from the heads, and 2 bolts(one per side) to release the carb bracket from the heads, then the only thing left is a breather and the throttle cables. I figured just hang the carb out of the way on the crash bars so I don't have to mess with the cables...
Too hot right now, I need to wait until it cools down later this evening! It would figure a giant ride rolled past my house with 100+ riders in it. I want this thing FIXED!!! LOL!
Thread Starter
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Road Captain
Joined: May 2011
Posts: 684
Likes: 9
From: Indian Head, PA
Ok, I disconnected the battery and removed the coil. I also removed the carb/manifold from the heads and have it hanging by big zipties from the right front turn signal. Next up is going to be disconnecting the exhaust, which I am not looking forward to since it's in poor shape and I really don't have the funds to replace it right now. Then I can get into actually tearing into the rocker boxes and the heads, right? I can now see that it will be worth my while to replace the base gaskets as well since I can see some oil leaks at the base of the cylinders. I also was able to inspect all the head bolts and check them and they all appear tight, even the one closest in vicinity to the head gasket leak, and wouldn't move readily even with a box wrench slipped in under the rocker box...
Please forgive the potentially stupid questions(my manual will be here Wednesday with my Cometic gasket kit), but should I drain the oil before I start taking the rocker boxes apart? Also should I do both cylinders at once or only take one apart at a time? Does it matter?
My bike has supposedly 130k miles on it. I really have no info about it's history. I know I should probably plan now to do rings and hone, as well as valve lap/seals, but I have never done this before, don't have the tools or parts and don't have the experience. I was originally hoping to get away with a quick gasket job, then possibly tear down this winter, but it is probably better to do it all now while it's apart...
Please forgive the potentially stupid questions(my manual will be here Wednesday with my Cometic gasket kit), but should I drain the oil before I start taking the rocker boxes apart? Also should I do both cylinders at once or only take one apart at a time? Does it matter?
My bike has supposedly 130k miles on it. I really have no info about it's history. I know I should probably plan now to do rings and hone, as well as valve lap/seals, but I have never done this before, don't have the tools or parts and don't have the experience. I was originally hoping to get away with a quick gasket job, then possibly tear down this winter, but it is probably better to do it all now while it's apart...
Stellar HDF Member
Joined: Apr 2009
Posts: 3,039
Likes: 11
From: Northern Ontario
Ok, I disconnected the battery and removed the coil. I also removed the carb/manifold from the heads and have it hanging by big zipties from the right front turn signal. Next up is going to be disconnecting the exhaust, which I am not looking forward to since it's in poor shape and I really don't have the funds to replace it right now. Then I can get into actually tearing into the rocker boxes and the heads, right? I can now see that it will be worth my while to replace the base gaskets as well since I can see some oil leaks at the base of the cylinders. I also was able to inspect all the head bolts and check them and they all appear tight, even the one closest in vicinity to the head gasket leak, and wouldn't move readily even with a box wrench slipped in under the rocker box...
Please forgive the potentially stupid questions(my manual will be here Wednesday with my Cometic gasket kit), but should I drain the oil before I start taking the rocker boxes apart? Also should I do both cylinders at once or only take one apart at a time? Does it matter?
My bike has supposedly 130k miles on it. I really have no info about it's history. I know I should probably plan now to do rings and hone, as well as valve lap/seals, but I have never done this before, don't have the tools or parts and don't have the experience. I was originally hoping to get away with a quick gasket job, then possibly tear down this winter, but it is probably better to do it all now while it's apart...
Please forgive the potentially stupid questions(my manual will be here Wednesday with my Cometic gasket kit), but should I drain the oil before I start taking the rocker boxes apart? Also should I do both cylinders at once or only take one apart at a time? Does it matter?
My bike has supposedly 130k miles on it. I really have no info about it's history. I know I should probably plan now to do rings and hone, as well as valve lap/seals, but I have never done this before, don't have the tools or parts and don't have the experience. I was originally hoping to get away with a quick gasket job, then possibly tear down this winter, but it is probably better to do it all now while it's apart...
- Draining oil is not important at tear down.
- no prob to take both apart at same time, mark the cylinders and heads as front and rear, get a piece of cardboard and make holes for the pushrods to fit into and mark rear exhaust read intake front exhaust and front intake and don't mix them up.
- if you flip the heads over and fill them with gas with an old set of plugs in the holes and let them sit over nite and if they don't seep they are probably good for the rest of the season
- for cylinders it wouldn't hurt to get them measured for out of round
The amount of miles on the motor if its never been torn down you may be do for top end anyway, too bad you couldn't have done compression test before tear down but with leaking head gasket it would have shown a problem anyway.
Let us know how your making out, there's a lot of great help here.
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Thread Starter
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Road Captain
Joined: May 2011
Posts: 684
Likes: 9
From: Indian Head, PA
Thanks for the info. It's pretty obvious that this motor has at least had the rocker boxes open since some one prior to me drilled the access hole for the left rear rocker lid screw...
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Road Captain
Joined: May 2011
Posts: 684
Likes: 9
From: Indian Head, PA
Ok, exhaust is off. Now I can start actually tearing into the rocker boxes and the heads. The exhaust really isn't in too bad of shape, but the right "Y" under the passenger floor board looks like it was modified with a piece of larger diameter pipe stitching together the header pipe with the muffler, and the stitching job was pretty poorly done. There were 2 screws drilled into each end of the added pipe and into the muffler and head pipe and these screws wallowed out the holes and fell out, allowing the muffler to swing around on it's hanger. If I can get the original "Y" piece and the right muffler clamp(I imagine it's supposed to match the left side, right?) then I should be able to put the stock exhaust back together without spending a fortune on a new exhaust system right now...