951 DI Engine Leak Test

[68ragtop]

So is the combustion chamber (case) loosing pressure or the water jacket?
Its leaking around the head bolts?

Sorry for asking again, just trying to understand a bit better.

I assume you are using soapy water & getting bubbles?

 

[tkarvelis]

It is leaking on the water jacket. Same place (near the rave nipples)

 

[68ragtop]

so its leaking at the parting line between the head & the cylinder at the arrows I added on your picture? both sides, are leaking?

 

[tkarvelis]

Yep. It is leaking more on the right side (in your pict) then the left side.

I pulled the plugs to listen if any air was blowing into the cylinder, and I did not hear any...

 

[68ragtop]

The crap thing about the head design is all of the head bolts only compress the combustion chamber edge of the gasket. The only thing that seals the water jacket is the trueness of both the head & top of the complete cylinder assembly. Not the greatest design IMO. Any chance the cylinder or head was dropped at any point? have they ever been out of your sight?. I believe you did drill out the gasket rivets & coated both sides, of both halves of the gasket?

I only ask because I had an oem gasket leak & it was from in-between the two layers. they don't put much of the black sealant coating on the inside. do you have a feeler gage? you could set the head on & see if you can find any anomolies in the fitment.

I worry a little that sanding the surface of the head "might" have taken a little more off the edges. when you pulled the gasket up last time did you see a consistent outline from the copper spray. it usually will stick to the surface, but get pushed super thin where the ribs in the gasket are.

 

[tkarvelis]

The crap thing about the head design is all of the head bolts only compress the combustion chamber edge of the gasket. The only thing that seals the water jacket is the trueness of both the head & top of the complete cylinder assembly. Not the greatest design IMO. Any chance the cylinder or head was dropped at any point? have they ever been out of your sight?. I believe you did drill out the gasket rivets & coated both sides, of both halves of the gasket?

It was not dropped that I am aware of. The head came from Nick as the head I had from the ski had a lot of pitting on the surface, and damage from a needle bearing.

I only ask because I had an oem gasket leak & it was from in-between the two layers. they don't put much of the black sealant coating on the inside. do you have a feeler gage? you could set the head on & see if you can find any anomolies in the fitment.

I do have a feeler gauge. I will clean the gasket surface tomorrow again. I will place the head on piece of granite and measure the space.

I am half tempted to try without any sealant, but I am 1000% sure it will be a waste of time.

I worry a little that sanding the surface of the head "might" have taken a little more off the edges. when you pulled the gasket up last time did you see a consistent outline from the copper spray. it usually will stick to the surface, but get pushed super thin where the ribs in the gasket are.

I did have a nice outline around the whole outside, except near the two bolts. It was thinner there.

I have used two different torque wrenches...

 

[68ragtop]

the compression on that rib of the gasket is everything. When you get everything cleaned up (again ) I would put the head on the cylinder & see what you can slide between the cylinder & head. really shouldn't be able to slip anything in there if there was such a thing as a "perfect" fit. you could even put the head bolts in & snug them. my guess is you have a gap on that edge thats just to large for the gasket to seal.

 

[68ragtop]

I have some of these parts stashed away. I'll pull them out to see what I find for a reference for you

 

[68ragtop]

Just checked for you. With a head placed on top of a cylinder (not bolted down & no gasket) the widest gap I could find was .0025" - .003" On this one it was on the Mag side kitty-corner from the air pump. I think a gap like that would get easily taken up from the gasket & copper spray. I have a feeling yours is going to be a bit more than that. Those marks left from the copper spray & gasket are tell tail.

 

[tkarvelis]

Yeah... Just a bit more. The head is flat... The jugs, not so much, greater than .008. I placed a flat edge on the jugs, and it rocks... The jugs are out, and hopefully going to a shop today.

Now I will need to order a new base gasket, It will need to be thicker, since the jugs will need to be trimmed.

I will also need new exhaust flange gaskets.

I am beginning to think that keeping the two stroke alive was written by someone richer then me

 

[racerxxx]

Yeah... Just a bit more. The head is flat... The jugs, not so much, greater than .008. I placed a flat edge on the jugs, and it rocks... The jugs are out, and hopefully going to a shop today.

Now I will need to order a new base gasket, It will need to be thicker, since the jugs will need to be trimmed.

I will also need new exhaust flange gaskets.

I am beginning to think that keeping the two stroke alive was written by someone richer then me

Forget about the money.............it's about the fun times to be had, that is priceless! You could throw in the towel and go buy a new Seadoo 4 stroke couch, they cost a lot more than an old 2 stroke. It's tough I get it, you're getting closer don't give up, it's time to push thru! If it were easy EVERYONE would do this crap.

 

[68ragtop]

I think thats why I like DI's, they fight you in every way possible. they sure make you think........

think twice about ever getting a second one that is.. jk

I have some oem thicker gaskets if you need one. See if they can give a measurement of what they take off, that would be a lot easier than trying to figure out what you need later. guessing if they take of .008 you will need a 7-8 hole if you had a 5 before. seems like most have 5 hole.

 

[68ragtop]

BTW, depending on your machine shops table/fixture, you might be able to keep the manifold bolted up? might be worth asking.

 

[tkarvelis]

Forget about the money.............it's about the fun times to be had, that is priceless! You could throw in the towel and go buy a new Seadoo 4 stroke couch, they cost a lot more than an old 2 stroke. It's tough I get it, you're getting closer don't give up, it's time to push thru! If it were easy EVERYONE would do this crap.

True... It is not so much about the money, but time.

My machine shop is a one man shop, and his mom is very sick, so he is tied up. We leave for vacation (to visit family) on the eastern part of PA, and between the kids activities Softball tournaments, Karate Tournaments, Boy Scouts, etc., I will not have a free weekend until the 27th of August.

Then once it is together, I need to paint it... Hoping for labor day weekend...

If not... I wont need to winterize it It will be sprayed down with oil, and waiting for me

 

[tkarvelis]

BTW, depending on your machine shops table/fixture, you might be able to keep the manifold bolted up? might be worth asking.

I pulled it. It is too much of a PIA to get the rings compressed and into the cylinder without the additional weight and bulk..

 

[tkarvelis]

I think thats why I like DI's, they fight you in every way possible. they sure make you think........

think twice about ever getting a second one that is.. jk

Yep... I have a second one. It is a lawn ornament right now... Need a complete new engine... Salt water and aluminum do not mix...

 

[68ragtop]

I use a pair of rubber tipped c clamps to hold the rings tight to the pistons. holds them just enough for the cylinder skirts to slip over. I highly recommend it. Those locating pins can be such a PITA, especially when your holding the weight of the cylinder & trying to keep everything square.

not sure how your going to paint it, but I found a combination of single stage omni automotive paints that when mixed together are spot on for color. I can dig up the paint codes if you want them.

 

[tkarvelis]

I never thought of the c-clamps. I will be looking into them. I have some, but i think mine are too big to use.

The head and jugs are at the machine shop. I should (if I was home) have them back next week. Hopefully I will be back early enough Saturday to get them, so I can work on them Sunday... The shop is closed Monday and Tuesday....

I purchased some silver engine paint I plan to use. It might be too silver, but i think once it gets a coat of WD-40 or two it will be OK.

 

[68ragtop]

Very cool. I'm guessing your head gasket cleaned up again? that copper spray stays somewhat workable for a long time. Always adds that finishing touch. The oem color is odd. its surely silver gray with a hind of gold in it.

 

[tkarvelis]

I think thats why I like DI's, they fight you in every way possible. they sure make you think........

think twice about ever getting a second one that is.. jk

I have some oem thicker gaskets if you need one. See if they can give a measurement of what they take off, that would be a lot easier than trying to figure out what you need later. guessing if they take of .008 you will need a 7-8 hole if you had a 5 before. seems like most have 5 hole.

What size thick gaskets do you have [MENTION=57696]68ragtop[/MENTION]? How much do you want for them?

 

[jhjesse]

i ended up not using any sealant the second time around and it worked for some reason.