On returning to seattle I found and ordered a new leather diaphragm for my motor. $50 mailed from California, I got the denso part instead of one made by Toyota. The theory is that the cause of my high idle is a deteriorated leather diaphragm is leaking air and causing the injector to provide too much fuel to the motor.
Part arrived in a nice little cardboard denso box, inside is a plastic bag containing the new diaphragm. The box is made from nice Japanese cardboard – you don’t see much paper like that here in the states.
Denso Box, new diaphragm in bag, and old diaphragm right after I took it out of the truck.
As box had a digital signature sticker – could this thing have been made recently? Is it possible that somewhere in Japan there is a workshop still making these? Someone packages up leather and sends it to denso where it is cut and made into fuel diaphragms?
I read up on the replacement procedure on the internet, have the assembly well-visualized as its apparently impossible to see well without removing the engine. Some folks say the diaphragm is difficult to remove even with the engine out. I’ll be leaning over the side with a headlamp on… huge sausage fingers. This won’t be fun.
There is lots of complaining on the internets. Lots of cases of dropped washers and nuts. Since the car won’t be drivable once I begin the procedure, I’d like to be sure I have everything I need before I start. The three recommendations that stuck with me:
1) Have a stool to stand on, I’ll have my head crammed against the base of the hood.
2) Have some needle nose with an angle tip.
3) Have a magnetic wand to retrieve anything I drop.
4) The tiny bolt inside is 8mm. Need a tiny 8mm wrench.
I go to 5 different stores for angle needle nose before relenting an buying a variety 6 pack at Harbor Freight. For $6. I am willing to pay more but you need to have it in stock! I also picked up a locking forceps at harbor freight for $2, in case I decide to try removing by pulling the pin.
Arrive back home for the big job. Clock starts at 1:30pm.
First I need to undo the housing. Appears to be 2 flathead bolts holding it on. The top drivers side flathead is threaded with mechanics wire which I snip.
I am able to undo the first using a tiny ratchet, takes 3 minutes. The second is a bitch, I’m on my stomach hands dug way in there undoing the flathead one click at a time. 5 minutes. And then I see that there’s another bolt underneath. Dang. Three bolts!
There is an arm that comes off the edic that is really where I need to have my hand. The near side of this arm is an easily removable press fit onto a knob. Just pull up and its free, tuck it out of the way.
Undo the 3rd bolt, again its tough, takes 10 minutes.
And then I see that the housing, while very loose, is being held by another flathead bolt that I can’t see. Dang, the thing is a square and there are 4 bolts. Feeling with fingers in the grime I can determine the direction the flathead is turned, line up the socket and slowly click away. Interesting that this flathead was pretty loose before I started. Maybe that is the actual problem? Maybe I just need to tighten it down and all is good? Make a solid seal? I’m too determined, I’ll get the diaphragm out and see. I can’t believe the diaphragm removal can be worse than these f’ing flathead bolts.
View of 3b fuel diaphragm in place with housing removed. Can see the tab at the base of the diaphragm slots into the injector.
It could be my difficulty is due to having the wrong tools. I have a screwdriver that will fit but there just isn’t room to grip and apply torque. I go with a small ratchet, an extension and a flathead tip but there’s just no place to turn it. Maybe there is a cable-tip screwdriver that would work but not clear how to hold the tip onto the screw. Flathead is just such a bad choice for something like this. In hindsight I should have replaced them with allen head bolts where the head grips the tool.
Finally get the last flathead out and housing is free. There is a spring that pushes the housing out which I remove and set in my tray with the flathead bolts. There is a hose coming from the top of the now-loose assembly that I hang the assembly from.
The diaphragm is picked out with my fingers, it comes out about 1.5″ before being restrained by the internal attachment. Pulling out with full extension of the leather I can peek inside if one eye is in exactly the right place: there is a brassy cotter pin on the drivers side. On the other side I can feel the 8mm nut. I’ve heard that the pin can be pulled so I try that first with some locking forecepts. I managed to take a few photos with my cell phone, very very hard to get a clear shot though.
View behind fuel diaphragm, there’s barely room to fit my thumb in there. On the left you can see the head of the cotter pin (that was manged, that I couldn’t remove.) On the right you can’t quite see the 8mm nut that must be undone…
Another view behind 3b fuel diaphragm. Cotter pin head visible on the left, 8mm nut barely visible on the right.
After 10 minutes of fiddling with the pin I give up, the pin is mangled pretty well and too hard to untie.
The mangled pin can be seen clearly.
Using the closed end of a tiny 8mm wrench I am able to undo the nut on the other side from the pin. Pretty much 10 degrees of rotation at a time. Honestly this isn’t nearly as bad as it was to remove the flathead housing bolts, just remember its a finite number of turns, take your time and breathe, stay loose. Finally the nut is loose enough to spin with my fingers. Reach in and turn with fingertips, ready to catch when its loose. I undo and manage to hold it, pull it out using fingers like a pair of chopsticks and place it in my tray. The whole time being careful not to bump the diaphram and displace the bolt which would cause the washer to fall out. Then reach back in and am able to score the washer, its like playing “Operation”. The trick is to thread thumb in behind the diaphragm and hold the end of the bolt, then reach in with first two fingers (of same hand of course) and tweezer the washer. Slowly! Score washer, place in tray and then Jangle-jangle the diaphragm assembly is free… jiggle diaphragm and out if comes. No problem, sort of jangly but nothing dropped. Time is now 2:30. I immediately reapply washer and nut so I don’t lose anything or forget how it goes together. There is an odd piece of sheetmetal that looks like it could be attached several ways, especially relative to a small tab on the diaphragm perimeter that must point DOWN on reassembly.
Old diaphragm as it came out of the truck.
The good news is that the diaphragm is torn, has 4+ tears that are 1+mm across. Good news because likely the torn diaphragm is the cause of the high idle. I didn’t do this for no reason and probably won’t need to go to a real mechanic for some expensive diesel specific tuning.
The leather diaphragm has metal crimped around its outside and there is a tab at the bottom of the metal. This tab fits into the bottom of the injector pump. Note to self: remember to reassemble with the tab on the bottom.
Old diaphragm and attachment assembly.
I considered reinstalling with the cotter pin and I play with the assembly on my patio. I straighten the cotter pin and play with the assembly but it really looks like the cotter pin is the more difficult route to take. For cotter-pin reassembly I’d need to insert the pin, then bend it out with very little access. Just need to see I guess…
I reassemble as before (checking against picture I took before disassembling it.) I did also straighten out, unmangle and rebend the cotter pin, in case that proves to be easier for someone in the future.
Finally I brace myself for what is supposed to be most difficult part: installing the diaphragm. The diaphragm bolts to a metal rod inside the injector pump, the injector pump rod has a hole near its end, horizontal. The rod moves front to back freely. Trick is to pull the rod out as far as it will go (not very far) then gently reach the diaphragm’s bolt in and hook it through the hole in the end of the injector rod. If you bump the rod it goes back in and is impossible to hook. Takes a three tries and some crimped fingers (press the end of the diaphram’s bolt with a stray thumb to keep it from falling apart.)
Once the diaphragm bolt is through the injector rod… its time for the most demanding part of the assembly which is replacing the washer and nut.
Old diaphragm from side that points out.
My fingers were pretty greasy which helped the small parts stick to them. Hold the washer between first and second fingers of right hand, place thumb against near side of diaphragm bolt, apply pressure with thumb to keep bolt from moving then very very slowly… slip the washer on. If you don’t hold the diaphragm bolt in place it will back out when you attempt to place the washer.
New diaphragm about to come out of the bag.
Now… place 8mm nut between first two fingers of right hand, very very carefully press diaphragm bolt again with thumb so as not to jostle the washer, then slowly place the nut onto the diaphragm bolt, and give it a meager desparate twist with your fingers. Spin it on as much as possible! Whew! Take a break and breathe a little!
Sort of like rock climbing!
Then use fingers and finally the 8mm wrench to spin the nut on, 15 degrees at a time, good and tight… Nothing is so bad now, the job is more than half over!
Finally I grease up the metal on the edges of the diaphragm (I used Phil Wood bicycle grease) to create a good seal, then I greased the spring a little, and finally pressed the housing back onto the injector. This is again awful!
Yes indeed these flathead bolts are still by far the worst part of the process. The housing is difficult to line up. The tiny flathead bolts are difficult to thread and reach. Took me a full 45 minutes to get the 4 bolts back on and tight. Finally I rewired with mechanics wire and replaced the edic arm.
Nothing really went wrong during this whole affair. I don’t think I’d do it differently the next time but you do need to be patient. I have pretty big sausage fingers and didn’t have trouble with space. I think I might look a little more for a better sized tool to remove those flatheads. I dunno what to do about them.
Last step, I started the truck. Nice low idle, solid at 600rpm. Much more clattery, as a diesel is supposed to idle. Drove to store and idle stayed at 600-650 even though the day was hot. I guess success.
Others have noticed better power, better fuel economy, etc. I notice the truck is much slower to rev, feels more lethargic. Drives ok, maybe more torque. Maybe I’m not used to needing to push the accelerator so far? I mean it drives ok, feels more like a truck now, but I sort of miss the high revving truck I used to have. Maybe mpg will improve? If so I’ll forgive it.
CanadianBJ 