Yong Wang (Polaris Virage copy) 700 water in cylinder bore, exhaust bolts loosening

[Jase]

Hi
I rebuilt the engine in my polaris virage (yang wong) ski

I have had problems with the exhaust bolts coming loose and causing water leaking into the hull.

Before and now after a rebuild.

Ive taken the exhaust manifold off to replace the exhaust gaskets and ive taken the barrels off to drill and tap the threads on barrel out to 10mm from the original 8mm.

The previous owner had put recoil inserts in the barrel and they aren't in the best condition and 1 or 2 have started to pull out.

I figure if i bring them all back to good condition with the oversize bolts and then use threadlocker i was hoping to solve this pesky problem.

Anyone know why these bolts are soo keen to escape?


My main question is really about water in the piston and bore on disassembly. Can a leaky exhaust gasket cause water to get into the bore, or would it need to be coming from a leaky head gasket.

All gaskets are new.

I have a valve on the engine flush kit which means i only have water running whilst the engine is running, then i turn the tap off, give the engine a few good revs then lift the revs up for about 10 seconds as i run either fogging oil or 2 stroke oil down the carby to coat the internals to prevent corrosion.

So i was a bit surprised to find not just clear signs of corrosion staining on the mag bore, rings etc but actual water still there from the ride/ flush the day before.
The main exhaust leaking was the mag cylinder which is the cylinder with the water ingestion.

Im not sure how water would be able to get into the bore when the exhaust gases should keep it out.
Is this possible?

Or should i go down the path of disassembling the barrel/ heads and get them shaved to ensure they are dead flat.
I tested them with a straight edge when rebuilding and they looked fine.

[casey67]

Loctite has to be used on those bolts. The heating/cooling , expansion/contraction of the parts will loosen the bolts. I think fine threads might also help.
At some point Polaris stopped using gaskets at the exhaust manifold/cylinder joint. Using a "high temp" silicone instead.
With exhaust headders on cars, you would need to retorque the bolts after the engine was run. I guess it's possible the gaskets are being compressed. Retorqueing would be difficult with Loctite.

Polaris recommended to have the exhaust manifold bolted in place before torqueing the cylinder base nuts. To make sure the cylinders were aligned perfectly with the exhaust manifold. Did you do it that way ?

The piston moves 2 ways. 1 pushing and 1 sucking. So yes, if you have water leaking at the manifold,it is possible to draw it into the cylinder. That is the first place I would look.
The head is sealed with an o-ring on Polaris engines. Is your o-ring thick enough ?

[nmpeter]

you might want to drill the bolts for safety wiring. harmonic vibration may be the issue and no amount of anything is going to keep the bolts tight, except wire.

[Jase]

Polaris recommended to have the exhaust manifold bolted in place before torqueing the cylinder base nuts. To make sure the cylinders were aligned perfectly with the exhaust manifold. Did you do it that way ?


The head is sealed with an o-ring on Polaris engines. Is your o-ring thick enough ?

Yeah i bolted the manifold to the barrels without a gasket and then tightened the lower base nuts on the barrels before undoing the manifold, fitting the gaskets and bolting the manifold back on to make sure they were straight.

I used blue loctite on the all the bolts except the one that i could easily apply a blow torch 2. So i used the red threadlocker on that one, I was worried i wouldn't be able to get the bolts back out if i needed to. Although i was still able to remove the red threadlocker bolt without heat or a great deal of force anyhow, but it did stay torqued up. So maybe the red threadlocker might be the go.

I did use an aftermarket kit but the o-ring was identical in size to the old one, so i assume it's the right size for the job.

[Jase]

you might want to drill the bolts for safety wiring. harmonic vibration may be the issue and no amount of anything is going to keep the bolts tight, except wire.

I might have to Google that to see what you mean.
Ive never done that to a bolt before but i have the equipment in my shed to do it, so I'll look into that option.

[kevinz]

Don't know if this will help you but when you install the cylinders leave them loose and install the exhaust manifold to align everything. Then install the cylinder base nuts you can get to and tighten them. Remove the manifold and install/tighten the other cylinder nuts, then reinstall the manifold for the final time.

[Jase]

Hi Kevinz

Yeah that's basically the method i used to assemble it.

[Jase]

So i haven't had time to reassemble the motor yet.

So for the last week ive had the cylinders inside down on a shelf with both bores filled up to the exhaust ports with radiator coolant and a clean rag underneath to check for any coolant leakage.
So far i haven't seen a drop of coolant on the rag in a week so i think the o-rings are sealing alright.

Could a leaky base gasket allow water into the engine?.

[casey67]

Not on the cylinders Polaris used on the Virage engines.
Snow mobile cylinders send water into the cases. How are the Yong Wang cylinders cast? Trace the water path into the 2 cooling holes below the large exhaust outlet hole.