rebuilding diesel engines

brf84500 · 10-09-2008, 05:21 PM

Hey guys, Im an automotive student and Im fairly familiar with rebuilding gas engines but I would like to try my hand at rebuilding a diesel. Could someone tell me the major differences in rebuilding a diesel? Is it common practice to replace cylinder sleeves as opposed to boring the cylinders as in gas engines? Do these even have sleeved cylinders or are they integrated into the block? Im probably thinking 5.9 cummins. Do diesel rebulds usually include new pistons?
How about heads? are valve guides and seats basically the same? Thanks, Brian

ykdave · 10-09-2008, 06:46 PM

Well, to say it simply, their isnt alot of difference in rebuilding a gasser and a diesel. Only you are dealing with a front geartrain (not much different than a gassers timing chain/belt) for the cam and inj pump and accy's(ps pump,vac pump, compressor)

The smaller cummins's do not have sleeves, they are a parent bore block, like gassers, this includes the 5.9. You wont find alot of smaller diesels with wet sleeves, i know for one, john deere does make some, we have a 4045JD (4cyl 4.5L) thats wet sleeved but none of our 3.3/3.9/5.9 cummins's are.

__________________
97 Ram 2500 / 5.9ctd / 5spd / nv4500 / 4x4 / np241
Starwheel cranked, no plate, autometer pyro and boost gauges, Single 4" stack, 33x10.5 Mud terrains, tons more to come

Last edited by ykdave : 10-09-2008 at 08:19 PM.

Robertb6963 · 10-09-2008, 07:52 PM

Subscribes.......

Good info here. And good post!

Welcome to the forum Brian.

__________________
-SOLD- 2000 Dodge 3500 DRW Quad Cab 4x4 @167k miles, 5 speed, patriot blue, Ranch-hand front/back, lift with BFG M/T, straight 4" pipe w/ 5" chrome tip, cracked block/head. I hate the 53 Block!!!

DIESELGUY84 · 10-09-2008, 08:38 PM

Brian,

Valve guides are where the stem of the valve rides in, valve seats are what the valve rests on to seal the combustion chamber.
As far as pistons go, they can usually be reused. Hone the cylinders and replace the rings.
All cumins B series engines are parent bore engines as stated above, however, there are over sized pistons available if the cylinders need bored.
If only one cylinder needs repaired, the block can be bored to accept a sleeve, then the sleeve bored to accept a standard bore piston, or whatever size the rest of the pistons are, then you only have to buy one piston. (belive me, they're pricey)
Hope this helps!
Eric

__________________
99 White QC 4X4 sport. 4in open exhaust, FASS95GPH, ADRENALINE, DDP 200hp styx, BD TWINS, ARP head studs, Truetrac rear diff. 5speed W/3850# Valair Dual Disc, Sirius, BD cooldown timer. Very special thanks to John @ www.hollandcourtsales.com 507HP/1130TQ 20.3 MPG

brf84500 · 10-10-2008, 04:20 PM

Thanks guys. I have an engine overhaul class coming up and the 5.9 is a possible victim. Where can I get a rebuild kit for one? Any major differences between model years besides the switch to 24v? (what year was that anyways?)
Thanks, Brian

***dezl*** · 10-10-2008, 04:31 PM

98.5 is when they switched to the 24valve

__________________
94 f350 w/ 95 6bt, Nv4500, Valair clutch, 370 Hp Marine Injectors, #4 fuel plate, dodgezilla hybrid turbo, 18* of timing, lazer cuts, 4k GSK, 60lbs springs and a lot more!

ykdave · 10-11-2008, 02:13 PM

and the dreaded 53 block!

Also, while its torn apart, dont forget to take care of the KDP

__________________
97 Ram 2500 / 5.9ctd / 5spd / nv4500 / 4x4 / np241
Starwheel cranked, no plate, autometer pyro and boost gauges, Single 4" stack, 33x10.5 Mud terrains, tons more to come

totalloser · 10-12-2008, 09:11 PM

Most overhauls you will see will need minimal work on the wear surfaces unless the engine has been severely abused. Modern chemical engineering makes rings practically not wear, to the point that running dry often wipes out a crank and rod, not the bore.

The only real wear issues on a properly maintained diesel will be; valve seats and valves, carbon buildup on valve stems, and soft items such as valve seals etc.

The main difference with diesels is the accommodation of the compression ratio. On IDI engines that run 23:1 give or take, the valve job can SIGNIFICANTLY change the compression ratio. DI engines such as the Cummins are much more forgiving as they are 16:1 (etc engine) or 16.5:1 (eth engine) so valve depth plays much less of a role in compression ratio.

However, valve face protrusion is still a major concern and worth careful measurement if you replace valves, and ESPECIALLY if you replace seats. This is mainly for preventing piston/valve contact, but is worth careful note. When determining course of action on the head, the fact that it is a DI engine may sway heavily towards minimizing work on the head. The main problem with valve/seat wear is difficulty starting the engine cold, but DI engines are MUCH MUCH more forgiving of being out of spec. IDI engines can be a NIGHTMARE to start if the valves are excessively worn. Most engines allow about .015" of wear to give you an idea.

I'm not sure about the Cummins, but all the IDI diesels I have cracked had multiple head gasket thicknesses to match compression accordingly. They were all IDI's though, so the Cummins MAY just have one. I dunno. Incidentally none so far has needed a complete overhaul, and some were SEVERELY abused.

If you don't do the head, I would encourage you to still pull the valves and clean the carbon off the stem/face as this will improve performance/efficiency measureably. You may be tempted to lap the valves, but if you do, go light. It's pretty easy to take them out of spec.

To summarize, the main difference in a diesel overhaul is the care regarding the valves and head.

PS, before ordering parts, I would consider taking measurements. IE ring end gap, plastiguage all the journals, and measure valve depth. You may be surprised.

__________________
01 24v 100hp tips, 4"ss BDbrake &steering brace PSCpump 1.5"dom steering tapped box 1.5"ram manual CAD switch dual carters 3.55's LSD, big shaft nv5600/241HD 6 35's inners pulled in (no spacer) Ugly black and thrashed!

brf84500 · 10-14-2008, 04:34 PM

thanks guys, good info. I will definately be going through all the journals, clearances, gaps, etc. for the purpose of the class. What is the KDP, IDI and DI?

NavyDood · 10-14-2008, 05:02 PM

How about this question. Why are the connecting rod caps angled? The Powercroak 6ohno has this design also. I have heard two different reasons. One reason is so the rod can fit in the bore and the other reason is it somehow centers the stresses better.

__________________
- 2004 2500 QC, SWB, 4x4, 48re w/Mag-Hytec DD, Smarty Jr, HOG 4" Exh, Modded Air Box w/Amsoil Drop In, Isspro Pyro/Boost/Tranny Temp, Quadzilla RPG w/fuel pressure option - B&W Hide-A-Ball w/5th wheel Companion - 06 Pilgrim Legends 30RE2SLF-5

10-09-2008, 05:21 PM	#1 (permalink)
brf84500 Newbie Join Date: Oct 2008 Posts: 4 brf84500's Truck Pics	rebuilding diesel engines Hey guys, Im an automotive student and Im fairly familiar with rebuilding gas engines but I would like to try my hand at rebuilding a diesel. Could someone tell me the major differences in rebuilding a diesel? Is it common practice to replace cylinder sleeves as opposed to boring the cylinders as in gas engines? Do these even have sleeved cylinders or are they integrated into the block? Im probably thinking 5.9 cummins. Do diesel rebulds usually include new pistons? How about heads? are valve guides and seats basically the same? Thanks, Brian

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10-09-2008, 06:46 PM	#2 (permalink)
ykdave Diesel Head Join Date: Feb 2008 Posts: 1,101 ykdave's Truck Pics	Well, to say it simply, their isnt alot of difference in rebuilding a gasser and a diesel. Only you are dealing with a front geartrain (not much different than a gassers timing chain/belt) for the cam and inj pump and accy's(ps pump,vac pump, compressor) The smaller cummins's do not have sleeves, they are a parent bore block, like gassers, this includes the 5.9. You wont find alot of smaller diesels with wet sleeves, i know for one, john deere does make some, we have a 4045JD (4cyl 4.5L) thats wet sleeved but none of our 3.3/3.9/5.9 cummins's are. __________________ 97 Ram 2500 / 5.9ctd / 5spd / nv4500 / 4x4 / np241 Starwheel cranked, no plate, autometer pyro and boost gauges, Single 4" stack, 33x10.5 Mud terrains, tons more to come Last edited by ykdave : 10-09-2008 at 08:19 PM.

10-09-2008, 07:52 PM	#3 (permalink)
Robertb6963 Diesel Freak Join Date: Jan 2007 Location: San Antonio Posts: 743 Robertb6963's Truck Pics	Subscribes....... Good info here. And good post! Welcome to the forum Brian. __________________ -SOLD- 2000 Dodge 3500 DRW Quad Cab 4x4 @167k miles, 5 speed, patriot blue, Ranch-hand front/back, lift with BFG M/T, straight 4" pipe w/ 5" chrome tip, cracked block/head. I hate the 53 Block!!!

10-09-2008, 08:38 PM	#4 (permalink)
DIESELGUY84 Cummins Nut Join Date: Mar 2008 Location: Fairplay Colorado Posts: 326 DIESELGUY84's Truck Pics	Brian, Valve guides are where the stem of the valve rides in, valve seats are what the valve rests on to seal the combustion chamber. As far as pistons go, they can usually be reused. Hone the cylinders and replace the rings. All cumins B series engines are parent bore engines as stated above, however, there are over sized pistons available if the cylinders need bored. If only one cylinder needs repaired, the block can be bored to accept a sleeve, then the sleeve bored to accept a standard bore piston, or whatever size the rest of the pistons are, then you only have to buy one piston. (belive me, they're pricey) Hope this helps! Eric __________________ 99 White QC 4X4 sport. 4in open exhaust, FASS95GPH, ADRENALINE, DDP 200hp styx, BD TWINS, ARP head studs, Truetrac rear diff. 5speed W/3850# Valair Dual Disc, Sirius, BD cooldown timer. Very special thanks to John @ www.hollandcourtsales.com 507HP/1130TQ 20.3 MPG

10-10-2008, 04:20 PM	#5 (permalink)
brf84500 Newbie Join Date: Oct 2008 Posts: 4 brf84500's Truck Pics	Thanks guys. I have an engine overhaul class coming up and the 5.9 is a possible victim. Where can I get a rebuild kit for one? Any major differences between model years besides the switch to 24v? (what year was that anyways?) Thanks, Brian

10-10-2008, 04:31 PM	#6 (permalink)
*dezl* 2321.41 miles from BBram Join Date: Oct 2007 Location: in a ghetto near you Posts: 1,806 dezl's Truck Pics	98.5 is when they switched to the 24valve __________________ 94 f350 w/ 95 6bt, Nv4500, Valair clutch, 370 Hp Marine Injectors, #4 fuel plate, dodgezilla hybrid turbo, 18* of timing, lazer cuts, 4k GSK, 60lbs springs and a lot more!

10-11-2008, 02:13 PM	#7 (permalink)
ykdave Diesel Head Join Date: Feb 2008 Posts: 1,101 ykdave's Truck Pics	and the dreaded 53 block! Also, while its torn apart, dont forget to take care of the KDP __________________ 97 Ram 2500 / 5.9ctd / 5spd / nv4500 / 4x4 / np241 Starwheel cranked, no plate, autometer pyro and boost gauges, Single 4" stack, 33x10.5 Mud terrains, tons more to come

10-12-2008, 09:11 PM	#8 (permalink)
totalloser Diesel Freak Join Date: Oct 2007 Location: Fort Bragg, CA Posts: 734 totalloser's Truck Pics	Most overhauls you will see will need minimal work on the wear surfaces unless the engine has been severely abused. Modern chemical engineering makes rings practically not wear, to the point that running dry often wipes out a crank and rod, not the bore. The only real wear issues on a properly maintained diesel will be; valve seats and valves, carbon buildup on valve stems, and soft items such as valve seals etc. The main difference with diesels is the accommodation of the compression ratio. On IDI engines that run 23:1 give or take, the valve job can SIGNIFICANTLY change the compression ratio. DI engines such as the Cummins are much more forgiving as they are 16:1 (etc engine) or 16.5:1 (eth engine) so valve depth plays much less of a role in compression ratio. However, valve face protrusion is still a major concern and worth careful measurement if you replace valves, and ESPECIALLY if you replace seats. This is mainly for preventing piston/valve contact, but is worth careful note. When determining course of action on the head, the fact that it is a DI engine may sway heavily towards minimizing work on the head. The main problem with valve/seat wear is difficulty starting the engine cold, but DI engines are MUCH MUCH more forgiving of being out of spec. IDI engines can be a NIGHTMARE to start if the valves are excessively worn. Most engines allow about .015" of wear to give you an idea. I'm not sure about the Cummins, but all the IDI diesels I have cracked had multiple head gasket thicknesses to match compression accordingly. They were all IDI's though, so the Cummins MAY just have one. I dunno. Incidentally none so far has needed a complete overhaul, and some were SEVERELY abused. If you don't do the head, I would encourage you to still pull the valves and clean the carbon off the stem/face as this will improve performance/efficiency measureably. You may be tempted to lap the valves, but if you do, go light. It's pretty easy to take them out of spec. To summarize, the main difference in a diesel overhaul is the care regarding the valves and head. PS, before ordering parts, I would consider taking measurements. IE ring end gap, plastiguage all the journals, and measure valve depth. You may be surprised. __________________ 01 24v 100hp tips, 4"ss BDbrake &steering brace PSCpump 1.5"dom steering tapped box 1.5"ram manual CAD switch dual carters 3.55's LSD, big shaft nv5600/241HD 6 35's inners pulled in (no spacer) Ugly black and thrashed!

10-14-2008, 04:34 PM	#9 (permalink)
brf84500 Newbie Join Date: Oct 2008 Posts: 4 brf84500's Truck Pics	thanks guys, good info. I will definately be going through all the journals, clearances, gaps, etc. for the purpose of the class. What is the KDP, IDI and DI?

10-14-2008, 05:02 PM	#10 (permalink)
NavyDood Cummins Nut Join Date: Dec 2006 Location: Solomons Posts: 405 NavyDood's Truck Pics	How about this question. Why are the connecting rod caps angled? The Powercroak 6ohno has this design also. I have heard two different reasons. One reason is so the rod can fit in the bore and the other reason is it somehow centers the stresses better. __________________ - 2004 2500 QC, SWB, 4x4, 48re w/Mag-Hytec DD, Smarty Jr, HOG 4" Exh, Modded Air Box w/Amsoil Drop In, Isspro Pyro/Boost/Tranny Temp, Quadzilla RPG w/fuel pressure option - B&W Hide-A-Ball w/5th wheel Companion - 06 Pilgrim Legends 30RE2SLF-5