Replacing Duramax LB7 Injectors 01-04 tips and hints
#231
12-05-2016, 12:58 PM
Great thread, great pics and commentary.
Howeverrrrrrrrrrrrrrrrr,,,,,
Not to be a wise acre, but I have a couple of comments to add from my own experience of having just done this;
1) Do NOT use ball ended Allen keys.
They have six very short lines of contact in the bolt heads and (given that all LB7s are now at least 12 years old) you are likely to run across a few tight ones if it has never been taken apart before and the ball end hex key will "burr out" the bolt head.
Sure, it is a PITA to use a 5mm 1/4 inch drive bit on the ones against the firewall, but that is NOTHING compared to the difficulty of getting one out with a wrecked head.
I was particularly paranoid about getting my allen key all the way down to the bottom of the cavities to get max contact. I flushed each one out with a blast of brake cleaner using the tiny plastic straw. Be careful if you do this, it can spray right back at Ya.
2) I disagree with the suggested tightening sequence for both upper and lower valve covers, it jumps from one end to other end, then to the middle and out to the ends again.
I prefer middle to ends, i.e. start at the one that is labeled 3 and continue in sequence, finishing on what are labeled in the original post as 1, 2.
3) Oh yeah, do NOT drop anything.
The front end on these trucks is a maze of traps for small parts.
There is a corollary of Murphy's Law, the smaller the part the less likely it is to get all the way to the ground. Something like that.
In any case have a garden rake handy in case you have to rake out parts or tools.
Howeverrrrrrrrrrrrrrrrr,,,,,
Not to be a wise acre, but I have a couple of comments to add from my own experience of having just done this;
1) Do NOT use ball ended Allen keys.
They have six very short lines of contact in the bolt heads and (given that all LB7s are now at least 12 years old) you are likely to run across a few tight ones if it has never been taken apart before and the ball end hex key will "burr out" the bolt head.
Sure, it is a PITA to use a 5mm 1/4 inch drive bit on the ones against the firewall, but that is NOTHING compared to the difficulty of getting one out with a wrecked head.
I was particularly paranoid about getting my allen key all the way down to the bottom of the cavities to get max contact. I flushed each one out with a blast of brake cleaner using the tiny plastic straw. Be careful if you do this, it can spray right back at Ya.
2) I disagree with the suggested tightening sequence for both upper and lower valve covers, it jumps from one end to other end, then to the middle and out to the ends again.
I prefer middle to ends, i.e. start at the one that is labeled 3 and continue in sequence, finishing on what are labeled in the original post as 1, 2.
3) Oh yeah, do NOT drop anything.
The front end on these trucks is a maze of traps for small parts.
There is a corollary of Murphy's Law, the smaller the part the less likely it is to get all the way to the ground. Something like that.
In any case have a garden rake handy in case you have to rake out parts or tools.
#2 is the actual tightening sequence from the OEM
#3 the fun spot is when you drop something and it ends up inside the cross member that the front plastic splash guard bolts up to, took me about 30 minutes to even locate there the ******* bolt went
#232
12-05-2016, 01:01 PM
Great write-up and pics, thanks for taking the time.
On post #2 you refer to a link regarding injector service (Duramax Diesel Fuel System - Fuel Injector Service). The link works but not much info there, I realize it's not your thread but curious if you know what happened to it. I'm a newb here and sometimes long time posters have updated info.
Thanks again
Phil
On post #2 you refer to a link regarding injector service (Duramax Diesel Fuel System - Fuel Injector Service). The link works but not much info there, I realize it's not your thread but curious if you know what happened to it. I'm a newb here and sometimes long time posters have updated info.
Thanks again
Phil
#233
12-06-2016, 05:10 AM
Agree on that "Special place" inside the cross member where parts and tools go to.
Every vehicle seems to have one.
Here's the thing on ball end allen keys;
{back in the day}
We were "instructed" in the early 60s that our jobs wold be on the line if we were caught with one within 20 ft of a Decca tape deck in one of those large gymnasium size computer rooms.
L-keys were all we were allowed, they worked fine then and I used one last month for the bolts up against the firewall.
If your hands get sore from the end biting you at the same spot for all 46 bolts just slip a deep socket over it - but ONLY for the initial loosening.
The snap on 5 mm alternative with a U joint is rumored to be over $40 - - a LOT compared to a whole set of L keys and with my luck it would disappear into that cross member on bolt #2.
I agree with the sequence ONLY for putting the bolts IN.
The end ones are the farthest apart and will align the cover.
The (largely hypothetical) possibility is that the head or valve cover faces are not flat and parallel.
Assuming you don't know whether they are like this () or like this )( the best way to get them together like this || is to start in the middle and work toward the ends.
{Yeah; picky, picky}
PLEASE don't take any of this the wrong way.
As others have said, this is a GREAT post and if I hadn't found it I would probably have unloaded the truck - $5K being too large a % of its current value.
Then what ? I would have shopped for a truck and probably bought what someone ELSE was unloading for undisclosed reasons.
Hey, thanks again.
Every vehicle seems to have one.
Here's the thing on ball end allen keys;
{back in the day}
We were "instructed" in the early 60s that our jobs wold be on the line if we were caught with one within 20 ft of a Decca tape deck in one of those large gymnasium size computer rooms.
L-keys were all we were allowed, they worked fine then and I used one last month for the bolts up against the firewall.
If your hands get sore from the end biting you at the same spot for all 46 bolts just slip a deep socket over it - but ONLY for the initial loosening.
The snap on 5 mm alternative with a U joint is rumored to be over $40 - - a LOT compared to a whole set of L keys and with my luck it would disappear into that cross member on bolt #2.
I agree with the sequence ONLY for putting the bolts IN.
The end ones are the farthest apart and will align the cover.
The (largely hypothetical) possibility is that the head or valve cover faces are not flat and parallel.
Assuming you don't know whether they are like this () or like this )( the best way to get them together like this || is to start in the middle and work toward the ends.
{Yeah; picky, picky}
PLEASE don't take any of this the wrong way.
As others have said, this is a GREAT post and if I hadn't found it I would probably have unloaded the truck - $5K being too large a % of its current value.
Then what ? I would have shopped for a truck and probably bought what someone ELSE was unloading for undisclosed reasons.
Hey, thanks again.
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2500HeavyDuty (12-17-2016)
#234
12-08-2016, 05:25 PM
Since doing mine a couple of weeks ago I have been scrounging around for a way to measure balance rates.
After MUCH messing around with a trial version of Torque Pro I followed a lead that got me to using my old Scan Gauge II.
Not "elegant" but it does the job and I have about 13years of use from it anyway, cost me $150 at the time IIRC.
Go to the Scan Gauge page, open the support page, go to manual, look up X-Gauges, follow ODB codes for GM, select LB7-LLY Duramax, punch 'em in.
OK, so you can only see 4 of them at a time, but it isn't in the same price bracket as EFILive.
Pleased to say mine are all WELL within spec.
After MUCH messing around with a trial version of Torque Pro I followed a lead that got me to using my old Scan Gauge II.
Not "elegant" but it does the job and I have about 13years of use from it anyway, cost me $150 at the time IIRC.
Go to the Scan Gauge page, open the support page, go to manual, look up X-Gauges, follow ODB codes for GM, select LB7-LLY Duramax, punch 'em in.
OK, so you can only see 4 of them at a time, but it isn't in the same price bracket as EFILive.
Pleased to say mine are all WELL within spec.
#235
12-17-2016, 12:41 AM
Since doing mine a couple of weeks ago I have been scrounging around for a way to measure balance rates.
After MUCH messing around with a trial version of Torque Pro I followed a lead that got me to using my old Scan Gauge II.
Not "elegant" but it does the job and I have about 13years of use from it anyway, cost me $150 at the time IIRC.
Go to the Scan Gauge page, open the support page, go to manual, look up X-Gauges, follow ODB codes for GM, select LB7-LLY Duramax, punch 'em in.
OK, so you can only see 4 of them at a time, but it isn't in the same price bracket as EFILive.
Pleased to say mine are all WELL within spec.
After MUCH messing around with a trial version of Torque Pro I followed a lead that got me to using my old Scan Gauge II.
Not "elegant" but it does the job and I have about 13years of use from it anyway, cost me $150 at the time IIRC.
Go to the Scan Gauge page, open the support page, go to manual, look up X-Gauges, follow ODB codes for GM, select LB7-LLY Duramax, punch 'em in.
OK, so you can only see 4 of them at a time, but it isn't in the same price bracket as EFILive.
Pleased to say mine are all WELL within spec.
four is better than none
i have out out of spec right now... it only shows out of spec when engine is cold and only when the rail pressure exceeds 12k psi at idle. the balance rate for that one injector is within "oem specs" its ok because it only tells you to check at idle and at gear when the engine is at operating temp. the engine does have a slight hiccup and the miss its noticeable in the exh tone untill it finally warms up. dont you just love diagnosing ****
luckily i have a LLY now so replacing one injector is a breeze now
#236
01-04-2017, 05:32 AM
four is better than none
i have out out of spec right now... it only shows out of spec when engine is cold and only when the rail pressure exceeds 12k psi at idle. the balance rate for that one injector is within "oem specs" its ok because it only tells you to check at idle and at gear when the engine is at operating temp. the engine does have a slight hiccup and the miss its noticeable in the exh tone untill it finally warms up. dont you just love diagnosing ****
luckily i have a LLY now so replacing one injector is a breeze now
i have out out of spec right now... it only shows out of spec when engine is cold and only when the rail pressure exceeds 12k psi at idle. the balance rate for that one injector is within "oem specs" its ok because it only tells you to check at idle and at gear when the engine is at operating temp. the engine does have a slight hiccup and the miss its noticeable in the exh tone untill it finally warms up. dont you just love diagnosing ****
luckily i have a LLY now so replacing one injector is a breeze now
Not sure that 12K psi at idle is right, I think mine is around 5K (memory, I saw it but didn't pay much attention).
Also, not sure that X-gauges work on the LLY (or LML) I think they are only programed for LB7.
It would be worth a try if you have a scan gauge, but probably not a good idea to buy a scan gauge for an LLY without checking into FIRST.
EDIT:
I just checked the scan gauge web site and YES INDEED the x-Gauge codes DO support LLY.
https://www.scangauge.com/x-gauge-co...7-lly-duramax/
:END EDIT
Last edited by ArrBee; 01-04-2017 at 05:45 AM.
#237
01-06-2017, 02:45 PM
#238
12-02-2017, 08:01 PM
#239
12-06-2017, 05:16 PM
