Engine repair or swap to LDS?

[gimpyrobb]

No reason to swap motors unless the block has a hole in it. An LDT can be tuned to make LDS power especially if you swap in the LDS rocker arms.

 

[ldmack3]

Good bit of smoke streaming out at idle after 2nd time working it in 2 weeks. Next day started it and no smoke until it stared warming up.

Lot of black smoke at higher temps until downshifted and got the temp down and RPMs up.
I've got the injectors out for service and will borescope the cylinders. My plan was to pull the heads for gasket replacement. After it got hot the first time the 3rd leak started. Appears to be oil.

 

[ldmack3]

I did LDS swap mine and agree with most that was said.

"I would pull the heads off the good takeout LDS...." like you said was exactly how my totally unplanned rebuild of a good running takeout engine started.
I just wanted to do the head gaskets. Not because they were blown, but they were seeping and its easier to do with the engine on a trailer.
But...while the heads are off I can...while the oil pan is off I should...while the pistons are out it is easy to..while I have the liners pulled.....would be dumb not to also replace....

Let that be a warning !




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Found a SS post where someone replaced his intake rocker arms with PN 11641735. Intake only rockers are all that is required?
None are available so far but I'm trying to get all my costs associated with the change.
Thanks

 

[cattlerepairman]

There is some agreement/disagreement over what makes an LDS vs an LDT. The intake rockers are definitely a difference; I do not think there is a contest.
The IP/HH may be different but an LDT with the LDS rockers and the fuel turned up will make LDS power.

When I redid my LDS I looked closely at what was different. The LDS appeared "better made" I.e. less crude, but that was really it. Later LDT had LDS features, such as piston oil squirters. The original turbocharger for the LDS was different but both C's and D's were bolted to LDS motors later on.

Not planning to start a flaming war, just sharing what I believe to be factual.

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[V8srfun]

There is some agreement/disagreement over what makes an LDS vs an LDT. The intake rockers are definitely a difference; I do not think there is a contest.
The IP/HH may be different but an LDT with the LDS rockers and the fuel turned up will make LDS power.

When I redid my LDS I looked closely at what was different. The LDS appeared "better made" I.e. less crude, but that was really it. Later LDT had LDS features, such as piston oil squirters. The original turbocharger for the LDS was different but both C's and D's were bolted to LDS motors later on.

Not planning to start a flaming war, just sharing what I believe to be factual.

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looking at this from a parts management prospective if you had 2 mechanically identical fuel pumps but they were adjusted, tuned, or preset to different fuel rates you would need two different part numbers. The community couldn’t find any significant differences in the fuel system other than some minor difference in injectors that I don’t believe anyone had flow tested to know what the real difference was. The turbos are all different but equally inefficient and leave much to be desired. The rockers are the only thing that would actually change the air flow characteristics of the engine. Like Gale Banks (the worlds leader in diesel performance) you need air before you add fuel. These engines are air starved and not only that but the whole induction system is designed in a way that is restrictive and heats the air change making it less dense. If you really want to improve one of these engines you need to free up intake restrictions and if possible find a way to cool the intake air charge. This is also why people have such positive results when switching to a 5 ton air cleaner and why everyone that has tried a aftermarket air filter with appropriate Cfm rating did not like it.

 

[ldmack3]

From what I have read many places the intake rockers are the biggest item effecting power. I'm also looking at increasing airflow. I'll probably add another cut out to the filter can before spending the money on a 5 ton air cleaner to see if it helps.

Appreciate everyone's help with this.

 

[V8srfun]

From what I have read many places the intake rockers are the biggest item effecting power. I'm also looking at increasing airflow. I'll probably add another cut out to the filter can before spending the money on a 5 ton air cleaner to see if it helps.

Appreciate everyone's help with this.

With the 5 ton air filter it is more about the higher Cfm rating of the element than the Cfm of the housing. You may not see any gain from the extra hole in your housing.

 

[cattlerepairman]

The community couldn’t find any significant differences in the fuel system other than some minor difference in injectors that I don’t believe anyone had flow tested to know what the real difference was.

I believe that the LDS initially had the single hole injectors before they switched to the two hole injectors, identical to the LDT, for cleaner combustion. I can attest from running both sets in the same LDS engine that the smokey single holers provide more "seat-of-the-pants" power. Both sets were pop-tested and set. I do run the two hole injectors because I do not need to disappear into a cloak of invisibility every time I hit the fuel pedal.
Real life says that I end up at the same max governed RPM and same top speed ("speed" being used loosely here) with either set.
So, again, injectors are more of a point-in-time difference between the LDS and the LDT, than a real design difference.

 

[V8srfun]

I believe that the LDS initially had the single hole injectors before they switched to the two hole injectors, identical to the LDT, for cleaner combustion. I can attest from running both sets in the same LDS engine that the smokey single holers provide more "seat-of-the-pants" power. Both sets were pop-tested and set. I do run the two hole injectors because I do not need to disappear into a cloak of invisibility every time I hit the fuel pedal.
Real life says that I end up at the same max governed RPM and same top speed ("speed" being used loosely here) with either set.
So, again, injectors are more of a point-in-time difference between the LDS and the LDT, than a real design difference.

So in a way kind of like a carburetor jet that was drilled out a little bigger it will be fat in the mid range but up top is just right.

 

[gimpyrobb]

The intake air is cooled. There is coolant passages in the intake. It has been tested by Bjorn(cranetruck) here on SS.

There are lots of different parts available for the motors. If memory serves, 5 different injection pumps, 2 different injectors, multiple pistons, etc. The biggest difference I've found in motors is the rockers, 2 hole injectors, some LDS injection pumps have a higher rpm limit, and the 5ton air filter CFM rating.

A set of pop tested and spray pattern adjusted single hole injectors will out-perform a 2 hole injector thats not poping at the right pressure(or pattern)!

 

[rustystud]

When I was on my Injection pump rebuild jag, I found that the LDS engine had different springs that allowed the RPM's to ramp up faster. This would account for faster spooling of the turbo. There were other small adjustments here and there, but basically the springs where the big deal.

 

[fleetmech]

When I was on my Injection pump rebuild jag, I found that the LDS engine had different springs that allowed the RPM's to ramp up faster. This would account for faster spooling of the turbo. There were other small adjustments here and there, but basically the springs where the big deal.

Changing out the governor spring was/ is a common mod on mechanical B series Cummins and for exactly those reasons. It gave a slight boost in RPM, which was great for driveability and HP, but its real advantage was in increasing the ramp rate and raising the rpm point where fueling would begin to taper off. Its not a big change either, usually going from 2800 rpm to 3k sometimes more, depending on how wild you wanted to go.

 

[ldmack3]

Good news and bad news.
Got my injectors back. Shop said the popped like new!
Got my new borescope!
At least 2 cracked pistons. #5 & #6.
After pulling the heads should all pistons/sleeves be replaced or just those showing damage?

 

[Mullaney]

Good news and bad news.
Got my injectors back. Shop said the popped like new!
Got my new borescope!
At least 2 cracked pistons. #5 & #6.
After pulling the heads should all pistons/sleeves be replaced or just those showing damage?
View attachment 875011View attachment 875012View attachment 875013View attachment 875014

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I dunno... It almost seems like replacing all is the way to go when you are that deep into the engine. You know, new bearings everywhere, new sleeves, full set of pistons. Then again too - that is how it is supposed to be done - at a reasonable cost.

Replace just the cracked parts maybe? Can you weigh and confirm that the parts you are buying is the same as the old?

 

[V8srfun]

Being that the pistons are probably cracked because of high egt I would change all of them and as far as the sleeves go it would be a decision based on cost.

 

[JasonS]

The intake is heated (this is described in the Continental literature). If the intent were to cool thi intake charge, they wouldn't be running the coolant exiting the engine through the intake.

I don't think anyone actually proved that the LDS rockers had a different ratio.

 

[V8srfun]

The intake is heated (this is described in the Continental literature). If the intent were to cool thi intake charge, they wouldn't be running the coolant exiting the engine through the intake.

I don't think anyone actually proved that the LDS rockers had a different ratio.

The coolant in the intake manifold is to reduce intake air temp not increase it. Turbo outlet temp is far higher than coolant temp. But regardless the air moves fast enough that the air would not be heated to manifold temp like everyone tries to claim with that argument. Most turbocharged engines have coolant in the intake manifold and it does not heat the intake charge. Plus any engine that has gotten up to temperature is going to heat soak the manifold to engine coolant temperature regardless.

 

[JasonS]

The coolant in the intake manifold is to reduce intake air temp not increase it. Turbo outlet temp is far higher than coolant temp. But regardless the air moves fast enough that the air would not be heated to manifold temp like everyone tries to claim with that argument. Most turbocharged engines have coolant in the intake manifold and it does not heat the intake charge. Plus any engine that has gotten up to temperature is going to heat soak the manifold to engine coolant temperature regardless.

Continental's design literature states that the manifold is heated to improve cold weather operation.

 

[V8srfun]

Continental's design literature states that the manifold is heated to improve cold weather operation.

that is fine but if you think about it you will see my point. The intake manifold would actually get hotter without coolant flow because of heat soak from the exhaust manifold. The coolant passages in the intake manifold do not heat the intake air charge especially when under load at full boost. Turbo outlet temps are higher than coolant temp when under full load and that is when Intake air temps are important. At idle or really low rpm the air may be moving slow enough to pick up residual heat but no one Is working their truck at idle so the real world effect is not important. To further my point if the coolant in the intake manifold was heating the intake air charge so well then the intake runner in the cylinder head would do the same thing. But that is simply not the case and if it was there would be no reason to use charge air coolers but every turbocharged engine made in the last 30 years has had them.

it is low on the priority list but one day I am going to be adding a turbo to my non turbo truck. Just to prove the point I will monitor egt add a charge air cooler and make no other change. The test will prove that intake air temp is effected by charge air cooling and it is beneficial regardless of intake manifold design. Every other car truck and machine community understands this but because a couple people that spread a rumor many years ago this community has been deceived. The worst part is that it would only take a couple minutes of study to disprove this misconception but no one wants to do the work they would rather just believe a old tale.

 

[cattlerepairman]

I do not doubt the assessment on the pistons. I do want to say that, when I rebuilt my LDS I took a deep breath when I saw the tops of my pistons and was convinced that #6 had a hole in it and others were at least cracked.

Panic post (#17) is here: https://www.steelsoldiers.com/threads/preparing-to-get-an-lds-ready-for-the-swap-questions.142077/

When I got enough oxygen back to my brain and cleaned the pistons up I saw....nothing. They were all fine. The "damage" was a very convincing trick by lighting and burnt residue. Judge yourself from the pictures.

Not saying that is what you are facing; just saying "look closely".


Some info on pistons as well in that thread.