What would cause bad knocking on hot start ?

[Dyno Bill]

Pulled into a camp site today and shut the coach down. We decided to repostion the coach after a few minutes.Upon restart the engine knocked extremely loudly and the protect engine light came on. Tried to rev it to "clean it out". When it would not rev I shut it down immediately. After letting it sit for about 5 minutes it started and seems to run fine now. Any ideas on what would cause this? 2005 C7 38,000 miles, never been apart.

[travelgirl]

I own a Cummins M-11 450 H.P Coach I'm sure our experts with advice who know about this will be along soon... I once had this problem when I first bought our coach and it shut down on it's own then restarted it a few hours later and all was seemed fine took it in to be checked when we got home they could not find nothing wrong but I still wonder too this day what it could have been so i will take a guess it could have been something loose inside like a bolt or something that chiped inside but thats just a guess let us know if you find out what it was

[dls461]

Was the engine HOT when you shut it down the 1st time or did you let it idle before shut down?

[spike45]

That would be a HEUI injector fault. Interesting that it cleared itself. It would not be a rod bearing knock. They are not that loud but exceptionally early timing on fuel injection produces a very loud knock.

[Dyno Bill]

Thinks far the replies everyone. We have been out of Verizon service for a couple of days. I wouldn't say it was hot when we shut it down, I didn't let it idle a bunch as we were going down hill into the campground.

Since this happened we have gone a couple of hundred miles and it has run great! Hope this keeps up as we are in CO and live in CA.

[Dyno Bill]

Originally Posted by spike45

That would be a HEUI injector fault. Interesting that it cleared itself. It would not be a rod bearing knock. They are not that loud but exceptionally early timing on fuel injection produces a very loud knock.

This is what I thought of when it happened, been reading to much!

[jauguston]

It may not be the HEUI. It could be a injector failing. I had a Terrible knock that would stop afrer a few minutes and it was a injector leaking fuel into the the top of the piston. A trip to a authorized CAT dealer and a hookup to the CAT diagnostic computer found it right away. One $550.00 (part only)rebuilt injector replacement and all is well. This was at 30,000 miles. The computer history printout showed another injector replaced under warranty at 14,000 miles for the same thing before I bought it.

Jim

[spike45]

Originally Posted by jauguston

It may not be the HEUI. It could be a injector failing. I had a Terrible knock that would stop afrer a few minutes and it was a injector leaking fuel into the the top of the piston. A trip to a authorized CAT dealer and a hookup to the CAT diagnostic computer found it right away. One $550.00 (part only)rebuilt injector replacement and all is well. This was at 30,000 miles. The computer history printout showed another injector replaced under warranty at 14,000 miles for the same thing before I bought it.

Jim

Jim,

HEUI is hydraulic electronic unit injector.....so we are both talking injectorr. The hydraulic aspect comes from a high pressure oil pump that provides the down stroke pressure on the plunger within the unit injector. The electronic determines timing of when the plunger begins the down stroke as well as how long the injector plunger is actively pushing fuel through the sac volume tip holes. I used to be a test engineer's assistant in the Caterpillar group that developed HEUI injectors for the Internation 7.3 V8 diesel (Ford Powerstroke). Later, Caterpillar took that knowledge to their own engine models.

[Macpeety]

Originally Posted by spike45

Jim,

HEUI is hydraulic electronic unit injector.....so we are both talking injectorr. The hydraulic aspect comes from a high pressure oil pump that provides the down stroke pressure on the plunger within the unit injector. The electronic determines timing of when the plunger begins the down stroke as well as how long the injector plunger is actively pushing fuel through the sac volume tip holes. I used to be a test engineer's assistant in the Caterpillar group that developed HEUI injectors for the Internation 7.3 V8 diesel (Ford Powerstroke). Later, Caterpillar took that knowledge to their own engine models.

On a sidenote:

My c7(05) went thru 4 injectors initially under warranty from cat. My understanding that cat went thru some bad injectors fresh out of the crate. It has always at times had some minor surging from 10-30 mph at wot and always corrects itself. I always assumed this was the computer cutting back on the fuel during this phase. Does this sound reasonable?

This started around 30,000 miles after a computer update flash by cat. I now have 110,000 with no other issues(knock on yellow). The Heiu pump was also replaced during the injector issues. My mileage has been around 8.5 which I understand is good for this setup. Should I be concerned?

Thanks

[jauguston]

Gary,

In a VERY technical way you may be right but if I walk up to the parts department at a authorized CAT dealer and tell the parts guy I need a injector for a C-7 he is not going to give me a HEUI. I think most will know what I want and it won't be a HEUI.

Jim

[Macpeety]

Originally Posted by jauguston

Gary,

In a VERY technical way you may be right but if I walk up to the parts department at a authorized CAT dealer and tell the parts guy I need a injector for a C-7 he is not going to give me a HEUI. I think most will know what I want and it won't be a HEUI.

Jim

The Heiu is a type of injector which is driven by a Pump(driven by oil). Your post is not clear as to what you are suggesting at a parts counter. Are you suggesting that a c-7 injector will not be a heiu for his year of mfg. If so you are wrong. It's an acert system with a heiu injector and a high pressure oil pump for the hydraulic portion of the injector firing.

[jauguston]

Maybe the engines you are familiar have a HEUI injector. Mine has 6 injectors AND a HEUI. The injectors are the devices that protrude into the combustion chamber and squirt diesel fuel into the combustion chamber under high pressure when required to create power. The HEUI provides engine oil under pressure to actuate the injector. This process is electronically controlled by the ECM triggering a solenoid on each injector that applies the HEUI pressure to the injector to make it squirt fuel.

Jim

[Macpeety]

How HEUI Injectors Work

Hydraulic Electric Unit Injectors

HEUI Injector History:
HEUI injectors are found on 7.3L & 6.0L Power Stroke diesels. The acronym HEUI stands for Hydraulic Electric Unit Injector, or more descriptively, Hydraullically actuated Electronic controlled Unit injector. An HEUI injector uses high pressure oil to pressurize fuel inside the injector. A high pressure oil pump (HPOP) is used to pressurize engine oil between approximately 500 - 3,000 (3,770 for 7.3L) psi. The high pressure oil pump is seperate from the engine's oil pump, which provides oil pressure for lubrication. Rather, the HPOP is dedicated to providing pressure to the HEUI injectors only. The HEUI injector was invented by Caterpillar and International adopted the technology for Power Stroke diesels between 1994 and 2007 before switching to a high pressure common rail system (6.4L). While the HEUI injector has become technologically outdated, it was considered cutting edge when it originally entered the market.

How HEUI Injectors Work:
HEUI injectors are relatively simply in design. The injector can be broken down into 2 basic sections, a fuel chamber and an oil chamber. A low pressure fuel pump supplies fuel to the injector, while a high pressure oil pump supplies pressurized oil to the injector. During the injection cycle, an actuator allows high pressure oil to enter the oil chamber of the injector body, applying pressure to an intensifier piston. On the other side of this piston is the fuel chamber of the injector. The intensifier piston pressurizes fuel at a rate of 7 times the oil pressure. Fuel becomes pressurized before an electric actuator releases it through the injector nozzle. Maximum fuel pressure for the 7.3L is 21,000 psi (7 x 3,000) and 26,000 psi for the 6.0L (7 x 3,770).

Now Argue with the above.....

[Macpeety]

Originally Posted by Macpeety

How HEUI Injectors Work

Hydraulic Electric Unit Injectors

HEUI Injector History:
HEUI injectors are found on 7.3L & 6.0L Power Stroke diesels. The acronym HEUI stands for Hydraulic Electric Unit Injector, or more descriptively, Hydraullically actuated Electronic controlled Unit injector. An HEUI injector uses high pressure oil to pressurize fuel inside the injector. A high pressure oil pump (HPOP) is used to pressurize engine oil between approximately 500 - 3,000 (3,770 for 7.3L) psi. The high pressure oil pump is seperate from the engine's oil pump, which provides oil pressure for lubrication. Rather, the HPOP is dedicated to providing pressure to the HEUI injectors only. The HEUI injector was invented by Caterpillar and International adopted the technology for Power Stroke diesels between 1994 and 2007 before switching to a high pressure common rail system (6.4L). While the HEUI injector has become technologically outdated, it was considered cutting edge when it originally entered the market.

How HEUI Injectors Work:
HEUI injectors are relatively simply in design. The injector can be broken down into 2 basic sections, a fuel chamber and an oil chamber. A low pressure fuel pump supplies fuel to the injector, while a high pressure oil pump supplies pressurized oil to the injector. During the injection cycle, an actuator allows high pressure oil to enter the oil chamber of the injector body, applying pressure to an intensifier piston. On the other side of this piston is the fuel chamber of the injector. The intensifier piston pressurizes fuel at a rate of 7 times the oil pressure. Fuel becomes pressurized before an electric actuator releases it through the injector nozzle. Maximum fuel pressure for the 7.3L is 21,000 psi (7 x 3,000) and 26,000 psi for the 6.0L (7 x 3,770).

Straight From Cat Website:

http://www.cat.com/cda/files/87761/7/pehp9526.pdf

Now Argue with the above.....

Be sure to click the link and read what cat says, I can also provide their toll free number if you would like to argue with them rather than us.....