Ed's 77 Terex 72-41

[mountainguyed67]

Here’s a 6-71, seems to be the same procedure.

 

[kshansen]

You are welcome to try that but I would not stand too close to it when starting.

I mean if the bad guys were coming fast over the hill and the only way to get out of the trouble I might but not on a machine I had money invested in or a real need to see it run for more than a few minutes.

Next time it decided to stick it could be at full throttle and you might only have a few seconds to get clear before parts start flying. Especially as your engine has the two screw levers on the control tube that means one injector stuck at full fuel means all are stuck at full fuel!

 

[kshansen]

Here’s a 6-71, seems to be the same procedure.

Nothing against the guy making those videos but when he was taking the "things" off the top of the valves and did not know they were called "Valve Bridges" it makes me question how much he really knows.

 

[mountainguyed67]

You are welcome to try that but I would not stand too close to it when starting.

I mean if the bad guys were coming fast over the hill and the only way to get out of the trouble I might but not on a machine I had money invested in or a real need to see it run for more than a few minutes.

Next time it decided to stick it could be at full throttle and you might only have a few seconds to get clear before parts start flying. Especially as your engine has the two screw levers on the control tube that means one injector stuck at full fuel means all are stuck at full fuel!

Thanks for that. The mechanic in the video even said that once the injectors are at that point, they’re on borrowed time. I thought “then why do it, just replace them”.

 

[mountainguyed67]

Nothing against the guy making those videos but when he was taking the "things" off the top of the valves and did not know they were called "Valve Bridges" it makes me question how much he really knows.

He’s a do it yourselfer who knows very little, but gets through it. My impression anyway. I still get to see the pieces involved.

 

[mountainguyed67]

So my next time up I’ll look for a stuck injector by having someone turn the engine over, and by carefully removing the pin so I can move it by hand to see if everything is moving freely? If an injector is stuck I’ll remove it and bring it down for match up and core?

Plus I have a larger diameter cheater pipe I can take so I can turn the engine by hand.

 

[kshansen]

I'm thinking I recall you have a Detroit service manual right? If so then if you have a Digital Calipers you can use them to adjust the injector timing or just use them to compare from one cylinder to the next. I know some people can get all kinds of fussy on setting things but for many applications close is good enough at least on an old Terex! Heck you could use a wooden ruler and get it close enough to know if it was going to run. Then you could get the genuine factory tool. Just took a quick look and the prices some are asking is crazy $50 to $80! Some are almost sane but others???

If you don't have the book let me know and I could scan a couple pages.

 

[mountainguyed67]

I have the service manual. I intend to read this section soon.

I have dial calipers.

What factory tool?

 

[56wrench]

i guess i am one of the very fussy guys. that was the way my instructor taught it. you used to be able to buy the timing pins individually-they weren't that expensive, maybe they are now. the timing pin is only about 2 1/4" long and may be easier to work with under your fuel tank. my theory is that if you are in there and its awkward to get at, do it right and only do it once. on the other hand, its your time and money- not a customer's and you are still diagnosing the problem

 

[mountainguyed67]

you used to be able to buy the timing pins individually-they weren't that expensive, maybe they are now.

Why would you want another one? In case you lose it? It’s worn?

 

[56wrench]

they were available in different lengths for different settings-ie. 1.484, 1.460,1.470, etc. you could only buy the one you need if you only needed it once. there should be a tag( if it is still there) on the valve cover which will indicate which one is needed if no one has changed the factory spec for whatever reason. ya they are small an could be possibly lost or the tiny tip could be carelessly bent

 

[mountainguyed67]

I don’t remember a tag, I can look closer.

 

[56wrench]

i added to the last post. the tag will have the engine model, s/n, engine rpm, hp, original timing spec, etc

 

[mountainguyed67]

There’s a tag with serial number on the side, I forget if there’s anything else on it.

 

[Bluox]

Look on the injector body for a round tag like N-55 .
Before you pull the injector You could measure the injector height with the valves down should be close enough .
Bob

 

[mountainguyed67]

Before you pull the injector You could measure the injector height with the valves down

For what purpose?

 

[Bluox]

For what purpose?

So you would know what height yours are set at.
Bob

 

[56wrench]

here is what the timing pin/gauges look like

 

[kshansen]

Here's a link to one I saw on Flesbay:
https://www.ebay.com/i/261148912702?chn=ps&mkevt=1&mkcid=28

Not saying that is the right one for your engine just an example of what they look like. Look at the top of the injector and there will be a small hole about 1/8 inch that the small end of that tool fits in and the wide part sits on the top that the rocker pushes against to measure the height. The one in the link is 1.460 that is the actual measurement of the height in inches. Different engine and injectors would be set to different spec's.

I was suggesting using your calipers to measure that dimension to see if one was way off from others. As Bluox says you need to measure the injector with the valves fully open on the cylinder, that puts the cam follower for the injector on the base circle of the cam for that cylinder.

EDIT! I see 56wrench posting while I was typing!

 

[kshansen]

There’s a tag with serial number on the side, I forget if there’s anything else on it.

Is there a tag on the side of the valve cover? Detroit was good about giving you all the special option information there if some one had not removed it!