# How many different ways to Prime a Diesel engine



## Sharpshooter77

I wanted to know how many different ways there are to priming different diesel engines. like the ford powerstrokes, or the dodge cummins, or the GM duramax. Also the bigger trucks like the internationals 4700s and what not. I know that the 1988 FL8000 dump truck that we have in work is primed by unscrewing the fuel filter and pouring 911 diesel into it, that truck has the inline CAT motor in it. I think that I am going to get in to diesel engines soon and would like to pick some info as I go along. Thanks, 
Shane


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## payton

yeah dont let them run out. then its primed when the key is turned.

payton


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## Sharpshooter77

But what if work has to be done to the fuel system. because wouldnt that cause air to get into the system.


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## Ole Tower

*How? to Prime a Diesel*



Sharpshooter77;393125 said:


> I wanted to know how many different ways there are to priming different diesel engines. like the ford powerstrokes, or the dodge cummins, or the GM duramax. Also the bigger trucks like the internationals 4700s and what not. I know that the 1988 FL8000 dump truck that we have in work is primed by unscrewing the fuel filter and pouring 911 diesel into it, that truck has the inline CAT motor in it. I think that I am going to get in to diesel engines soon and would like to pick some info as I go along. Thanks,
> Shane


Shane--remove the Fuel Filter & make sure its FULL or Fill it UP! & break loose each injector line --just a turn or So?--Crank the engine & watch air bubbles as they Escape from the Injectors--when streight Fuel runs Out--NO more Bubbles--tighten that Injector back UP!--& as the injectors --One by One!--get primed--the Engine will run Rough --shake Rattle & Roll?--as each primed injector clears itself of AIR--& finally will Run Smooth --Shut it Down--& clean UP all the Fuel thats spilled Out--once its Clean--start it UP again & re-check for any Leaks? --NO Leaks?-Your DONE!--OleTower--


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## the_experience

Here's how I prime my 6.6 Ford/New Holland Brazilian diesel.

1. Fill with fuel and fix any obvious air leaks.
2. Fill both fuel filters doing one at a time
3. Unscrew the primer handle from the side of the injector pump
4. Pump until you get pressure...it can take 50 pumps or 500 pumps
5. Screw the primer back down and crack the bleeder screw on the fuel filter assembly
6. Repeat 3-5 until there is no air seen coming out of the bleeder and you get pressure at the primer pump after 5 or so pumps.
7. Fire it up and give it as much pedal as it needs to run until it smooths out

Yep, it sucks. I try and avoid doing it, but it's tough to avoid with the veggie oil fuel system. I have since installed an electric pump on both the veggie and diesel feed lines so I can electrically prime it....turn on the pump and crank until it starts...much easier.


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## justme-

unless you crack the line to the injectore you don;t need to prime anything. Change of fuel filter requires filling the filter before you put it on just like an oil filter, then following the owner manual instructions- for the Cummins there is a manual button/lever on the lift pump you work until you feel resistance and you're done. 

I have never had to prime past the filter on my Ram- ever. Honestly- if you're competant enough a mechanic to be doing injection work onna high pressure diesel system, you should already know the rules, precautions, and methods for injector priming.... sorry to be harsh, but it's true. Fuel at the injector line pressure of current generation engines (and back over 15 years!) will slice through skin down to bone- it's not something to play with unless you know what you're doing.


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## Green Grass

All the new diesel's are self priming all you have to do is turn the key on a couple times and the system is primed older systems depend on the truck most have a screw you remove then a primmer ball by the filter housing somewhere. NEVER prefill the filter housing it can give you contimated fuel and dirt in the system.


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## justme-

Green Grass;393721 said:


> All the new diesel's are self priming all you have to do is turn the key on a couple times and the system is primed older systems depend on the truck most have a screw you remove then a primmer ball by the filter housing somewhere. NEVER prefill the filter housing it can give you contimated fuel and dirt in the system.


READ THE MANUAL on YOUR truck- The newest I have dealt with was 01-ish- it was NOT self priming and I have never heard of one. Remember NO engine is self priming beyond the injector pump any more than a brake system is self bleeding! If you're talking primer balls- like rubber squeeze balls like weed trimmers and out board boat motors, you're either not talking vehicle engines or you're talking 60's man.

ALWAYS prefill your filter, just like your oil filter- can you contaminate your fuel- sure. But you can contaminate your oil filter the same way. That's like reasoning not to turn the faucet off after you wash your hands because the handle is contaminated with the dirt from your hands when you touched it turning it on.
Common sense here- add dirty fuel get contamination.


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## Green Grass

justme-;393963 said:


> READ THE MANUAL on YOUR truck- The newest I have dealt with was 01-ish- it was NOT self priming and I have never heard of one. Remember NO engine is self priming beyond the injector pump any more than a brake system is self bleeding! If you're talking primer balls- like rubber squeeze balls like weed trimmers and out board boat motors, you're either not talking vehicle engines or you're talking 60's man.
> 
> ALWAYS prefill your filter, just like your oil filter- can you contaminate your fuel- sure. But you can contaminate your oil filter the same way. That's like reasoning not to turn the faucet off after you wash your hands because the handle is contaminated with the dirt from your hands when you touched it turning it on.
> Common sense here- add dirty fuel get contamination.


NEVER EVER prefill your filters!!! that is straight from Cummins. On and 01 cummins there is a screw u remove on the top of the filter housing tap the key let the pump run when the pump stops if fuel has not came out yet then tap the key again and repeat intill fuel comes out the bleader. On Older cummins there is a little primmer ball on the side of the block to blead the filter cause there is no lift pump. On new cummin's 03 and up the systems are self priming that includes the high pressure side of the system (after the Injection pump) and why on earth do you prefill your oil filter. If you would like to tell me i am wrong again feel free but i work on the trucks every day so i know the drills.


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## justme-

If you don't prefill your oil filter you're running the engine with no oil pressure until the filter is filled- which can be over 1 minute- an eternity for an engine.

I think I just figured out what you're referring to when you say "bulb". The 1996+ lift pump has a rubber covered button for priming the lift pump. *Ok, I withdraw my statement*. You don't have to prefill the filter as working the priming button will fill it....eventually. After the 3rd filter change, you'll be prefilling yours too. I've been prefilling mine for so long now I had to really think about how the system works. Cummins mechanics have no problem with prefilling, as long as you use common sense- keep the fuel clean.

1995 and back has a lever style primer on the lift pump (they have had lift pumps since atleast the late 1980's, and probabily longer).
I just read the service manuals for an 01 and 03 diesel and I stand corrected.
The screw on the 01 is the banjo bolt for the transfer line. I don't understand why they have that step, since they don't do that for any other version (probabily necessary because of the injector pump used now that I think about it)

I stand by my 1st statement that unless you really know what you're doing don't touch a line after the injector pump. I was not thinking of priming the lift side, after Ole Towers post my mind has been straight on the priming being the high side.

This underscores the importance of reading the service manual for this kind of stuff and not relying on others for everything.

My apologies for my erronious, and incorrect statements.


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## Green Grass

No problem as long as the truck runs when u are done who cares



justme-;394052 said:


> If you don't prefill your oil filter you're running the engine with no oil pressure until the filter is filled- which can be over 1 minute- an eternity for an engine.
> 
> I think I just figured out what you're referring to when you say "bulb". The 1996+ lift pump has a rubber covered button for priming the lift pump. *Ok, I withdraw my statement*. You don't have to prefill the filter as working the priming button will fill it....eventually. After the 3rd filter change, you'll be prefilling yours too. I've been prefilling mine for so long now I had to really think about how the system works. Cummins mechanics have no problem with prefilling, as long as you use common sense- keep the fuel clean.
> 
> 1995 and back has a lever style primer on the lift pump (they have had lift pumps since atleast the late 1980's, and probabily longer).
> I just read the service manuals for an 01 and 03 diesel and I stand corrected.
> The screw on the 01 is the banjo bolt for the transfer line. I don't understand why they have that step, since they don't do that for any other version (probabily necessary because of the injector pump used now that I think about it)
> 
> I stand by my 1st statement that unless you really know what you're doing don't touch a line after the injector pump. I was not thinking of priming the lift side, after Ole Towers post my mind has been straight on the priming being the high side.
> 
> This underscores the importance of reading the service manual for this kind of stuff and not relying on others for everything.
> 
> My apologies for my erronious, and incorrect statements.


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## Yaz

*Bleding air in fuel filter and lines in a Duramax*

For the Duramax, there is a built in plunger pump on top off the filter under the the hood. Open the black plastic air bled valve and press down the plunger about 10-15 times until fuel comes out the air bled screw the tighten up the air bled screw. Press the plunger a few more times until it is hard to press down. At the point you good to go start her up.


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## snowman2025

on the new 6.0L i know that you don't have to fill any of the filter compartments. its a good idea to fill the oil, but the 2 fuel filter cannisters you don't. even one of them is on its side and impossible to fill. you turn the key a couple times and listen to it prime up.


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## 04superduty

snowman2025;394142 said:


> on the new 6.0L i know that you don't have to fill any of the filter compartments. its a good idea to fill the oil, but the 2 fuel filter cannisters you don't. even one of them is on its side and impossible to fill. you turn the key a couple times and listen to it prime up.


yeah that one on the frame rail would be real hard to try to fill. it being parallel with the ground and the stupid drive shaft in the way. the one under hood would be eaiser though.
how do you fill a cartridge style filter?


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## SNOWLORD

Fill filters, put compressed air line in tank with a rag around the top to make a better seal crack injector lines let her buck


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## LD4850

Powerstrokes are self priming & self bleeding. All you need is fuel & a good battery.
Prefilling filters is something that won't hurt your engine but if you have an oil related failure, You'll NEVER convince me that it was because the filter was put on dry. The amount of wear you get won't matter in at least 1,000,000 miles & by then you need a rebuild anyway on most trucks.


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## Philbilly2

Cummins is the only one that I have been able to crack an injector on. Older Cummins runs on the same concept as many tractors do. The old stlye known as a P-pump (pre 98 1/2) or even the 98 1/2 to 02 with the VP44 injection pump. The new Cummins run a system that Chevy has been running the the D-Maxes. It is refered to as common rail. This means that your CP3 pump fills a common rail of fuel then each cylinder is fed off that rail. Not near as easy to reach injectors as the direct injection on the Dodges. I know d-maxs are not self priming. Yaz nailed the way to prime them on the head. I have never been able to do in in 10-15 pumps though, my experence.


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## Ggg6

Depending on the type of engine there are several ways to prime. As stated some engines are relatively self priming, some require manual priming. There are several types of fuel systems and the methods differ from one to another. Even the mentioned issue of filling the filter isn't consistent from mfg. to mfg. Cummins them self have gone both ways on this issue in the years I have been a diesel tech.


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## 84deisel

on my cat motors I always fill the filter,usally with trans fluid and injector additive and the prime is located on the filter block, just turn to unlock and pump till it build resistance .oif you dont, it is not going to start.


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