Perkins Compression Tester

[lifeofreilly57]

Does anyone know of a company that makes a compression tester adapter for a Perkins 4108?
It would have to go in the fuel injector bore, there are no glow plugs in the 4108 head.
Currently the only way I know to do it is to destroy an injector to use it as an adapter.

[skipperpete]

Originally Posted by lifeofreilly57

Does anyone know of a company that makes a compression tester adapter for a Perkins 4108?

It would have to go in the fuel injector bore, there are no glow plugs in the 4108 head.

Currently the only way I know to do it is to destroy an injector to use it as an adapter.

I’ve got 2 compression testers one is an entry level model from “Supercheap”, the other a high end recording model, both came with a universal “dummy injector” and an assortment of specialized injectors for GM, CumminsPT, Cat 3208 and some for engines I’ve never encountered. Yes , it’s ok to sacrifice an old injector for the cause if your gauge didn’t originally have the accessories...... and technically, you don’t need to actually destroy it. Just take out the needle and make a thread adapter to suit the injector pipe connection and plug the leakoff port with an appropriate short bolt. Those Perkins Pintle nozzles have a pretty big hole in the end.

[lifeofreilly57]

Originally Posted by skipperpete

I’ve got 2 compression testers one is an entry level model from “Supercheap”, the other a high end recording model, both came with a universal “dummy injector” and an assortment of specialized injectors for GM, CumminsPT, Cat 3208 and some for engines I’ve never encountered. Yes , it’s ok to sacrifice an old injector for the cause if your gauge didn’t originally have the accessories...... and technically, you don’t need to actually destroy it. Just take out the needle and make a thread adapter to suit the injector pipe connection and plug the leakoff port with an appropriate short bolt. Those Perkins Pintle nozzles have a pretty big hole in the end.

Thanks for the reply. Yes, I figured I'd try to find one ready made but have found nothing in the open market, apparently there's not enough demand for them. I have access to a lathe and did consider making one, then seeing if theres any interest in selling them, that's a project for another time. I wonder if there's enough interest out there to make it worth my while.
I have fittings for most of the popular engines but this one has been one I found hard to find. Of course it's the engine my own boat, so it figures it's one of the few I've had a problem finding. I need it to find out whether it's a small issue, or a not so fun issue. Go figure.
Thanks for the reply, I'll be hitting the hardware store tomorrow morning.

[markxengineerin]

I just made one for my Yanmar 4JH2E yesterday- for a leakdown test- but same thing would work for a compression test. It's a piece of aluminum turned down to the right diameters, and with a flat milled into each side to fit the injector mounting bracket (white piece in picture). The same tip seals from the injector are re-used. It worked well- I was debating if I should use steel instead, but this was 3x faster to make and was strong enough for the purpose. No need to go crazy with tightening it down- just enough to stop any leaking. My results: 99.5, 99.5, 99, 99.5- happy with the rebuild after about 150 hours. If making them for resale, steel would probably be better.


Edit- an idea that might save time specifically for a compression test- they make rubber tip adapters that you have to hold in manually. I've used them on SI engines, not sure how they'd work for diesel and the higher pressures. Maybe woth a try https://www.fc-moto.de/epages/fcm.sf...hoCApUQAvD_BwE

[sailingunity]

I bought this for my Westerbeke and was able to find one that worked, though the injector retainer didn't have the right spacing, I made one out of maple.

https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

[skipperpete]

That’s a very good test result, you certainly did a good job with the rebuild.

[skipperpete]

A word of caution while discussing compression tests, whenever you have a potential pneumatic pressure of 400-500 psi you really need to keep out of the way of the test rig. The injector adapter properly fixed in place should be ok with a limited area presented to the pressure but if for some reason that adapter is above the sealing surface, the “piston”area is dramatically increased to the point where theres enough force to strip the hold down screws and fire the adapter out of the hole like an exocet missile. Thats also why its really risky to try blowing out injectors by releasing the hold down screws a half turn and spinning the engine over, as soon as that injector lifts off the seat the 400 psi is acting on the entire diameter of the body, not just the diameter of the nozzle and will have no trouble popping off the hold down threads and rapidly exiting the tube.
Just saying, ....,be aware of the risks.

[lifeofreilly57]

I made an adapter from a hydraulic pipe fitting and my least used tester fitting. Welded the fitting to the adapter. The pain in the neck was getting the pipe fitting. Apparently the injectors are metric, even though the rest of the motor is put together with American standard nuts and bolts.
Hardware stores usually only carry american sized brass fittings, which I cant weld to, fortunately I found a steel fitting at a local Pirtek hydraulic hose supplier, they were quite happy to help me and it was reasonably priced.