028 Crankcase Pressure Test

[DanAyo]

I want to pressure test the crankcase on an 028. I am trying to put pressure in through the pulse line. The exhaust and spark plug hole are plugged. How do I plug the intake manifold (rubber boot)? I have tried several things and the boot plug is leaking. I think the rubber bumps in the outside portion of the boot may be causing the problem.

Any help is appreciated.
Danny

 

[grizz55chev]

I want to pressure test the crankcase on an 028. I am trying to put pressure in through the pulse line. The exhaust and spark plug hole are plugged. How do I plug the intake manifold (rubber boot)? I have tried several things and the boot plug is leaking. I think the rubber bumps in the outside portion of the boot may be causing the problem.

Any help is appreciated.
Danny

Pics might help.

 

[DanAyo]

Pics might help.

 

[PV Hiker]

I have a collection of plastic plugs that would fit into the boot.

 

[DanAyo]

I have a collection of plastic plugs that would fit into the boot.

I have plugs from a MityVac and have tried using the worm clamp to seal them. But no luck with that.

I fear damaging the rubber boot if I clamp down too tightly with the worm clamp.

 

[PV Hiker]

I have a series of scrape cap and such. I was able to find just the right diameter slightly bigger to push into the boot. No clamping needed. Look around your shop, kitchen for something the right diameter, needs not to look pretty. Might have to keep a finger on it while pressure test, as you only need 7 to 10 psi.

If I get some product that has a protective cap I save them for later, for this such occasion. I can't remember if I used one from the mini vac kit as it may have been too small.

 

[DanAyo]

I have a series of scrape cap and such. I was able to find just the right diameter slightly bigger to push into the boot. No clamping needed. Look around your shop, kitchen for something the right diameter, needs not to look pretty. Might have to keep a finger on it while pressure test, as you only need 7 to 10 psi.

If I get some product that has a protective cap I save them for later, for this such occasion. I can't remember if I used one from the mini vac kit as it may have been too small.

I found a brass tubing nipple that fit. Before clamping the rubber boot was wrapped several times with electrical tape. It held pressure!

Thanks for the help.

 

[president]

I want to pressure test the crankcase on an 028. I am trying to put pressure in through the pulse line. The exhaust and spark plug hole are plugged. How do I plug the intake manifold (rubber boot)? I have tried several things and the boot plug is leaking. I think the rubber bumps in the outside portion of the boot may be causing the problem.

Any help is appreciated.
Danny

Duggan, the shop talk guy, pushed the boot into the cyl side ,the used an av mount into the boot and
sealed it off with a zip tie

 

[sawfan123]

Find a piece of rubber, like an old inner tube. Cut a gasket out using the carb as a template.
After punching mount holes, put it on the manifold then mount carb. That will seal it. Vac test first, then pressure.

 

[Plink-plonk]

I have the mighty vac too. However I also have the manifold block tools designed to sit where the carb does and that’s also where o connect the mighty vac for a leak down.

I would suggest replacing all the carb housing, use a longer price of pipe on the pulse line. And place a rubber blanking slide between the carb and the boot and tighten the carb up to close off the intake.

 

[DanAyo]

Blocking off the intake with a piece of rubber and the carb is not the best solution for me. To install the carb, the fuel tank and undercarriage would need to be installed. The undercarriage would block a major part of the crankcase seal and also the jug to crankcase seal.

Using a copper nipple (used for water plumbing) and wrapping the rubber manifold boot with electrical tape worked well and got the job done.

I appreciate everyone’s help!

 

[Mad Professor]

Hardware stores sell an assortment of rubber corks of various sizes.

 

[cgeb]

I agree with the rubber under the carb if the unit is together. I was just thinking (and I havent tried it) for disassembled meaning out of the case or covers off, I wonder if the right sized PVC pipe with a cap on it would work? If you could slide it into the boot and zip tie or clamp around the boot? Sometimes I want to check things before I put it back into the case.

 

[PV Hiker]

Good tip for rubber corks. Find, use whatever is going to work for what you have in front of you. Pill bottles, spice containers, etc. I made a aluminum block off plate for the carb replacement but some times a plug for the boot works. Sometimes the impulse hose is unavailable and I use a sparkplug insert with a hose nipple to test from.

Duct tape if you can get a good enough clean surface area for a seal. Use what ever you can find.

 

[OneStaple]

Duct tape if you can get a good enough clean surface area for a seal. Use what ever you can find.

I’ve used this successfully a few times, although I use gorilla tape (a little more sticky). You need to remove the rubber boot and clean the opening where the tape will go well (I use acetone). The tape alone will hold pressure/vacuum for a minute or two on its own if you have a good connection. I usually lightly clamp a circular piece of wood over it to keep the tape from lifting on the pressure test.

Tyler

 

[TheTone]

Hardware stores sell an assortment of rubber corks of various sizes.

View attachment 940650

I also like to use rubber stoppers because you get to check the integrity of the manifold as well as the connection to the cylinder. I bought a graduated range of sizes from The Widget Company (www.widgetco.com), from large manifold size down to fuel line size. To get a really good seal, use a thick grease like Dow-Corning high vacuum grease (used to use this when doing vacuum distillations back in the day). Be sure to use a large enough stopper or the top can slide down into the manifold.

 

[HarleyT]

Grease up a finger and stick it in there.

 

[SAWTECH1]

I want to pressure test the crankcase on an 028. I am trying to put pressure in through the pulse line. The exhaust and spark plug hole are plugged. How do I plug the intake manifold (rubber boot)? I have tried several things and the boot plug is leaking. I think the rubber bumps in the outside portion of the boot may be causing the problem.

Any help is appreciated.
Danny

I have used a threaded hose barb, which is screwed into a pipe coupling which is held on by a screw clamp. Stihl does make the proper fitting that connects to the carb boot, makes the job real easy.