55Mph Detonation. . .

[Srjeeper]

Funny you should bring that point up DH.

As an 'Old timmer' the saying always use to be that when a diesel let go, "Overrevs takes out the top of a motor and under revs (lugging) takes out the bottom".

Now I'm not saying that's the case in either one of these failures, but those were always first considerations back in the day....long before computer controled engines.

 

[doghead]

Your showing your age, Bill!

 

[topo]

FMJ I ended up with 3 m35 motors two with out turbo and one set up for a turbo .I have used a starter off one of them for my 5 ton . they are not locked up or have any holes in the blocks . they are all mounted on wooden motor stands . I don't have much in them . and if you are going to rebuild a motor at least this one is already out of the truck . kenny

 

[FMJ]

FMJ I ended up with 3 m35 motors two with out turbo and one set up for a turbo .I have used a starter off one of them for my 5 ton . they are not locked up or have any holes in the blocks . they are all mounted on wooden motor stands . I don't have much in them . and if you are going to rebuild a motor at least this one is already out of the truck . kenny

Hey Kenny,

PM me with a price for the motor/motors. I'm short 2 now. . . And since Nick (bgekky3) can't take his truck home with him right now, I've got wheels to make a pic up!

Thanks,
Ed

 

[Goose2448]

That sucks FMJ.

 

[G-Force]

Can you see if you can find the rod cap and post pictures of it......that is if there is anything left of it. Hopefully it is in the oil pan

 

[stumps]

Funny you should bring that point up DH.

As an 'Old timmer' the saying always use to be that when a deisel let go, "Overrevs takes out the top of a motor and under revs (lugging) takes out the bottom".

Now I'm not saying that's the case in either one of these failures, but those were always first considerations back in the day....long before computer controled engines.

Hmmm? That sounds backwards to me in a way. When you lug a motor, you increase the head pressure greatly, and that is when you blow head gaskets, and cause excessive ring wear. It is also when you burn the top out of a piston... But when you over rev, the extreme force necessary to turn the piston around as it slams up and down stretches rod caps, and breaks rod bolts.

As my grandmother used to say, "I'll have to study on that some more..."

-Chuck

 

[Srjeeper]

Not really stumps, diesels are for the most part low rpm, hight torque motors. 'Lugging' puts excessive strain on the lower end of the motor while 'over-revs' gets the top end moving at speeds it was never designed to operate at.

Push rods bend, springs break or bounce, valves move at excessive rates of travel and before ya know it, parts touch that were never designed to touch and Bang.

Lugging results in the loss of kinetic energy and bottom end parts are then pushing and pulling at stress levels they were never designed for.

Now this is or course an over simplification, but it was the wisdom of the day, yet still holds true today from my experiences.

 

[Jake0147]

According to that rule of thumb the top end failures aren't head gaskets so much as floated valves, bent pushrods, and the collateral damage from pushing broken valve pieces through a cylinder and if equipped, on through the turbo. Lower end failures are more rod/bearing failures, because the slower the engine turns, the closer the peak pressure is to TDC where the crankshaft has nowhere to go, as well as the fuel/air charge being at it's maximum compression, it makes forces where what it takes takes to turn a piston around becomes negligible.
As with most rules of thumb, it applies better to some engines than to others. Due to it's evolution and specific characteristics (long stroke, high RPM design, heavy pistions, limited strength of head bolts/studs relying heavily on gasket strength) I wouldn't necessarily apply this rule directly to a multi. It's an engine where too many variables are varied.

Of the pictures I've seen (which have mostly been here, so most of you have seen the same) it seems to me that it's <usually> a bolt failure, if the bearing is shot. (there are a few exceptions)
I have to wonder about the torque specs, the reusability of the hardware, the correct application of service procedures, etc. The rod bolts should not be the weak link.

 

[dittle]

The best way for you to know what has happened to any engine in its lifetime is for you to be the only one who has used said engine. 99% of the trucks that we own (by that I mean SS members) have engines/drivetrains that have seen use and/or abuse that we will never be aware of. To try to say these failures are caused by a lack of spin on filters/pre-lubing systems or the rebuilds not being done correctly at wherever is taking a guess as we (the owners) don't know the full history of the engine.

 

[mudguppy]

... Lugging ... will really stress the rod bolts ... .

Could you elaborate on this theory?

 

[stumps]

Not really stumps, diesels are for the most part low rpm, hight torque motors. 'Lugging' puts excessive strain on the lower end of the motor while 'over-revs' gets the top end moving at speeds it was never designed to operate at.

Push rods bend, springs break or bounce, valves move at excessive rates of travel and before ya know it, parts touch that were never designed to touch and Bang.

Lugging results in the loss of kinetic energy and bottom end parts are then pushing and pulling at stress levels they were never designed for.

Now this is or course an over simplification, but it was the wisdom of the day, yet still holds true today from my experiences.

Sounds reasonable.

I have never seen a thrown rod on a diesel used in commercial service.... Obviously, I have had limited exposure to such things... The typical commercial diesels I have used have governors set to some maximum safe continuous RPM setting. And they typically have gearing that easily produces unsafe over the road speeds at the governor setting.

That clearly doesn't describe the MF deuce.

-Chuck

 

[dittle]

Sounds reasonable.

The typical commercial diesels I have used have governors set to some maximum safe continuous RPM setting. And they typically have gearing that easily produces unsafe over the road speeds at the governor setting.

That clearly doesn't describe the MF deuce.

-Chuck

Ain't that the truth!!!!! But considering what the Deuce/MF combo was designed to accomplish it is matched up well.

 

[stumps]

Ain't that the truth!!!!! But considering what the Deuce/MF combo was designed to accomplish it is matched up well.

I have a feeling that if we all stop pretending we can go 56 to 60 MPH in our stock deuces, we will see a drastic reduction in thrown rods.

-Chuck

 

[dittle]

Agreed

 

[wsucougarx]

Agreed also

 

[shootiniron]

I'll go with that too!

 

[FMJ]

I have a feeling that if we all stop pretending we can go 56 to 60 MPH in our stock deuces, we will see a drastic reduction in thrown rods.

-Chuck

So I was all good at 55?. . .

This turning into a "I told you so thread"

 

[badgmc56]

It doesn't take a rocket scientist to figure this out. The first time I drove my deuce at maximum said speed and heard the engine just about jumping out of the hood, I said forget this. I only run at 2200 rpm and no more than 48 to 50 miles per hour. You have to use a little common sense when driving a vehicle that was built for off road down the freeway.

 

[shootiniron]

Ed,I think that with your experience and knowledge of these trucks you above alot of folks here know when and when not to push them.