I need help with exhaust bolts...BAD!!

[Waternut]

Basically I can't keep the 3 bolts attaching the head pipe to the exhaust manifold. The manual calls out for the bolts to be torques to 14.5 ft-lbs with loctite. That lasts about 10 minutes.

So I originally torqued them more and that lasted a bit longer but no good. I ended up stripping the manifold on one hole and stepped up the bolt size to 7/16" and retapped the manifold for all three. Using generic torque values for the new bolt has allowed me to step up the torque quite a bit and the bolts still rattle out. I've tried many other things including lock washers but right now I'm up to using lock washers and JB weld on the threads and it's lasting about an hour before the bolts back out.

What else can I possibly do to keep these bolts in place? I'm running out of ideas here. About the only thing left I can think of is ordering special bolts and drilling the pipe and manifold to fit a cotter pin. That or weld the pipe the manifold.

 

[oxnard111]

we kept having the same problem on a coffman dry pipe on a 750sx... ended up having to time cert the manifold. Never came off again.

 

[Waternut]

we kept having the same problem on a coffman dry pipe on a 750sx... ended up having to time cert the manifold. Never came off again.

Time cert the manifold? What is that?

 

[oxnard111]

Time cert the manifold? What is that?

similar to a helicoil, but better

 

[Pablo]

Johnny,

Was that you out today. I swore I say you pass my dock at least one time.

 

[WFO Speedracer]

One word for you STUDS.

 

[Waternut]

Johnny,

Was that you out today. I swore I say you pass my dock at least one time.

Yes it was but it couldn't have been too much more than that. I had so many problems with this ski that I can now hear and feel when something is wrong. When the throttle response disapears, the bolts are coming loose...when I hear a faint vibration, a bolt is missing and when the ski starts to die at idle, at least two of the bolts are gone and the gasket is blocking the exhaust.

I can't find time-serts anywhere so I've bought helicoils. Had to buy all new drill bits too because I didn't have what it called for. Now the shank is too big for my drill. WTF?!?! :lame:

 

[Waternut]

One word for you STUDS.

I thought about studs but what good are they if I can't keep anything in the manifold in the first place...just means I'll have a nut and a stud to fish out of the engine bay.

 

[Kennay]

I thought about studs but what good are they if I can't keep anything in the manifold in the first place...just means I'll have a nut and a stud to fish out of the engine bay.

Not true. When you use a stud with a nut on it, the nut acts sort of like a jam nut would against another nut. Stud + lock washer if you think you really need it, and you will be good to go :afro:

 

[WFO Speedracer]

As you know I am a Seadoo tech,Seadoos have had problems with snapping off and backing out exhaust bolts for years,the fix was to replace all the bolts with studs,they do have about 30% more clamping force than bolts ,which is why all the auto guys use studs exclusively on their engines for head,and main retention,typically if the threads in the manifold are repaired with helicoils,timeserts,etc and the correct locktite is used they don't back out.

 

[DEEZEE]

I have the same ski and the same problem. I put an american coarse thread heli coil in and red lock tite on the bolts. No problems as of yet. What kind of pipe are you running?

 

[DEEZEE]

Do you think the motor is not shimmed correctly? I never had a problem until I rebuilt the motor and put it back together.

 

[WFO Speedracer]

Usually its a problem with shimming or a engine harmonics problem,the engine harmonics can be problematic and can be caused by different weight pistons,also all engines have an rpm range where the engine harmonics are at their worst,if the engine is operated most of the time in this range you will have these problems.One cure is changing the pitch on the prop to get the engine to operate at a different rpm,you only need to move it by 500 rpm or so to be effective.

 

[Waternut]

Well I have installed some helicoils because they are the only thing that was available to me without ordering. I torqued those things to 31 ft-lbs so hopefully that will be enough and it will hold up. Wish me luck...

 

[djkorn1]

Time certs for sure. I did mine. They have NEVER came loose and it has been 3 years.

I stripped all 3 of the stock holes. (they sucked.)

 

[dajnglst]

Were you able to get time certs in stainless ?

I had similar issue with old school riva solid pipe. (red)

Aluminum was so corroded even after helicoil the bolts could back out after jumping the boat. I use aircraft lock wire and rigged them all up.

They do sell some stainless lock wire washer set ups for hex style bolts.

I have even made my own inserts from stainless plumbing tube. Can only make them 10mm long or the thread is too stretched out from the die.

It can be done.

 

[ryan75]

let them get all rusty like mine!!!