Pressure Testing???

[rahtreelimbs]

Before you go to all this trouble try spraying brake cleaner around likely places for air leaks while the saw is running g and hooked up to a tach. If you have a leak you will notice a change in rpm.

Ben.....funny you chime in on this. This happens to be the EHP modified 361 that you sold me some years back. Belongs to a friend now.

 

[bwalker]

I regret letting that one go.

 

[rahtreelimbs]

I regret letting that one go.

I think I have the saw fixed......will know this weekend.

 

[Wood Doctor]

After getting some answers on another thread I'm kinda believing my saw might not have an air leak, it might just have a kinked fuel line which would cut off the fuel..

If that were the case, it seems like the engine would be starved for fuel and die altogether rather than run lean.

 

[a. palmer jr.]

If that were the case, it seems like the engine would be starved for fuel and die altogether rather than run lean.

I was working on three saws at the time, an 029, an 039 and a 361, all had fuel issues. Turned out the new fuel lines I bought for the 029 and 039 were defective and the 361 had a impulse hose that came unhooked on one end. They're all running now and none needed a pressure/vac test. The 039 has other problems but nothing a bunch of money won't cure so it's sitting for awhile..

 

[RedneckChainsawRepair]

Is that you Rich?

Washer muffler mod.

 

[rahtreelimbs]

Is that you Rich?

Washer muffler mod.

Yep.....I did that......saw stillots running?

 

[rahtreelimbs]

Update in this 361. Upon tearing the saw down to pressure test it I find the impulse line barely connected to the case. I removed the hose only to find that it is almost as hard as a rock. Replacing the impulse line solved the problem.......saw two/four strokes great.......great speed and power. No load is 14,200 rpm. I was surprised as I thought that the impulse line was hard lined thru the case and with years of saw dirt built up it was hard to see. I did route the line differently. To make it easier to put a new line I took it up and over right beneath the air filter. Before doing a pressure/vaccuum test it pays to do a thorough degreasing of the saw.......would have seen the impulse line easier. Thanks to all who helped. Nothing like a hard cutting EHP modified saw!!!

 

[a. palmer jr.]

With hard impulse line and a fairly soft av system they would come loose. That's what happened to mine, I put the line back on but haven't gotten a new line yet. It needs to flex.

 

[Whitty21]

For finding an air I just put the power head in water up to the base of the cylinder air look for bubbles. I hadn't done a pressure/vaccuum test in a while ....hence the reason for this thread.

I generally cheat the tank and just fill a spray bottle with soapy water. Spray around potential leak spots and look for bubbles, can be a bit of a pain for crank seals though

 

[Ted Jenkins]

In more than 50 years of two stroke experience I have never pressure or vacuum tested any motor. Race motors on dirt bikes could go up to 50 hours of operation before the crank got rebuilt, new bearings, new piston, new clutch, check transmission over, and all new seals. My saws have either had low hours of use or had the bottom end rebuilt so not sure when to check. Would it be just as easy to pull the bearings and replace the seals as to go through the testing procedure? Are the testing procedures bullet proof as far as detecting weak or worn out components? It appears that the intake and exhaust needs to be sealed up to check bottom end? Right? Thanks

 

[redunshee]

In more than 50 years of two stroke experience I have never pressure or vacuum tested any motor. Race motors on dirt bikes could go up to 50 hours of operation before the crank got rebuilt, new bearings, new piston, new clutch, check transmission over, and all new seals. My saws have either had low hours of use or had the bottom end rebuilt so not sure when to check. Would it be just as easy to pull the bearings and replace the seals as to go through the testing procedure? Are the testing procedures bullet proof as far as detecting weak or worn out components? It appears that the intake and exhaust needs to be sealed up to check bottom end? Right? Thanks

E
I pressure test if I detect an issue with idling or if saw dies when put on its side. Replacing bearings isn't very common unless there is radial play in them. Replacing seals is much easier than bearings. Yes, you need to block the carb and exhaust in order to pressure/vacuum test.

 

[pioneerguy600]

In more than 50 years of two stroke experience I have never pressure or vacuum tested any motor. Race motors on dirt bikes could go up to 50 hours of operation before the crank got rebuilt, new bearings, new piston, new clutch, check transmission over, and all new seals. My saws have either had low hours of use or had the bottom end rebuilt so not sure when to check. Would it be just as easy to pull the bearings and replace the seals as to go through the testing procedure? Are the testing procedures bullet proof as far as detecting weak or worn out components? It appears that the intake and exhaust needs to be sealed up to check bottom end? Right? Thanks

The saw crankcase needs to be split to change bearings but the seals can be replaced without splitting the cases. It only takes 15 - 20 mins to pressure test a saw, it would take a half day to split and change out bearings. It takes about 30 mins to change the seals only.

 

[a. palmer jr.]

I mostly do pressure tests on saws that aren't mine. It might save the customer money rather than take half a day to replace a part that isn't needed. Sometimes a good carb cleaning is all that's needed..