I have some new glow plugs and thought while I was at it, why not check compression. I got the plugs out (thankfully they were Beru, maybe the originals) using a 1/4 ratchet, 6" drive and a 10mm socket.

It's looking like I have to remove the fuel lines to get the compression tester in place (it's much thicker than the 1/4" extension bar). Is removing the fuel lines SOP for testing compression on these 6.9's? Anything I need to know before taking the lines off (other than not bending them)? Are they pressurized, if so how do I pressurize them?

 

I don't think removing the hard lines is SOP for a compression test, but if it makes your life easier, go for it.

The pictures I've seen make it look like the best thing to do is disconnect all the hard line connections at the injection pump and at each injector, and lift all the hard lines off the engine as a unit (leave the rubber vibration dampers attached to the lines). That will ensure that everything's lined up correctly when you go to replace the lines later, and should minimize any accidental bending.

No, the lines won't be pressurized when the engine isn't running. You might get some fuel out of them when you take them off, but nothing to worry about.

 

I did a compression test recently, I don't recall having to do anything with the fuel lines.

Is your compression tester extra bulkier for some reason?

 

I bought this one:
Direct Indirect Diesel Engine Compression Injection Tester 12pc Test Kit Gauge | eBay

I didn't see a 90 degree angle adapter, but will check again. pretty sure I won't be getting the hose routed in between the hard fuel lines over a couple of the glow plugs. Maybe I can bend the rubber hose under and around the hard lines.

 

If I take the spider off, I'll have to bleed the lines when I put it back on right? I'm kinda interested to see how strong/weak this engine is before I go much further. The glow plugs are already out so I'll have to do a cold test (know it's not preferred and it will appear my engine is worse than it is).

Still, if the cold test is close to being within tolerance then I will go ahead with replacing the injectors, return lines, and probably the IP as I hear it's best to do that at the same time as the injectors. I'll probably also pull off the middle pan and replace one or more lifters. If compression is way out of synch I'll probably just put the new glow plugs/controller/relay on and let it go for a while.

 

No way I can get the compression tester hose over a couple glow plug holes wihtout removing the fuel spider.

I went ahead and ran a check on the front right cylinder just for kicks. Let it cycle ten times with a battery charger attached. Got out to see the guage read 375 PSI. Test was done cold. I was going to try another hole that's easy to get to, but I can't get the guage to reset. There's a schrader valve on the hose, but pressing it in fully does nothing. It's stuck on 375.

 

You didn't read the warning label.

WARNING: Single use only!!!

 

375 is a good solid number, especially on a cold engine. I usually only crank them over 3-4 times. Also good to see how many revs it takes to get to max if possible.


Have you tried smacking it on something? I find more often than not that does the trick for me

 

I just tried tapping it on the vice.. no luck. I also tried holding in the schrader valve while tapping, nothing there either. Chinese junk. Couldn't even use the damn thing more than once.

 

The one I got from Harbor Freight works nicely, you have to get the more expensive one, the $30 one doesn't fit:


https://www.ford-trucks.com/forums/1...l#post13091074

 

I think i would question the reading as well.

Might try removing the valve core all-together and see what happens, could be a bad core but i doubt it.

 

I got the Harbor Freight one ($110 on sale with 20% coupon).

I cannot get to the glow plug holes with the 90 degree angle connector in the HF kit unless I loosen the fuel lines. Even then it's hard. I thought it wouldn't be a bad idea to pull them off, since I'll be replacing the injectors soon anyway. May pull the cover so I can get to the lifters (one ticks loudly).

Question, how the **ll are ya'll removing the bottom-most fuel line nuts on the IP? I could barely get the second from the bottom nuts loosened. Using a flare wrench just no room to turn it (wrench sandwiched between manifold and IP).

 

Also, is there an easy way of stopping fuel from flowing out the IP when I'm turning the engine over on the compression test? I thought I remember reading I could remove a wire, but I can't find the thread now.

 

Pull the wire to the fuel shut off, description here. Ignore the picture, not relevant.

I really don't recall having to remove/move my injector lines, but I can't say with 100% assurance that I didn't, so maybe I did and suffering from CRS.

 

I always leave the lines attatched to the IP and pull the IP.... but that isnt really going to work for you in this instance i guess