Oops.

My post didn't make sense.

I meant to say I take it the turbo IS a variable vane type.

Need to check before I post otherwise my iPhone comes up with it's own opinion!

has anyone thought about the mass of the pistions..and their size?
stop a second..
2.8L 4 cylinders..no of any other 4 cylinder engine that size..no most are smaller
most VW TDI at 1.9liter..much smaller

2.8L is about 2x the size of my 6cyl motorcycle with a 6k redline...

maybe the redline should be 3500/3200 rpm not 4000 rpm..

for turbo failures..soot and lack of cool down times..

Geordi..you ran with and EGT..after running empty..what was the EGT when you pulled into a parking place?
400 - 600 - 800..300F?? I hope closer to 400F or less..oil cokes..synthetic oil not so much but at 800F who knows..this add to the snoot problem..and bearing wear..

just my thoughts..

-dkenny

_________________
84 BB school bus, DD8.2L turbo ->the transmission died..too expensive to fix..it'll be heading to the scrap yard..4/11)..Bus gone to Scarp 8/23/11
06 Liberty CRD
'99 dodge ram 2500 quad cab, 4x4, 24v
all Biodiesel powered when its warm enough

I agree, at 4000 rpm with that size cylinder letting loose, it can hammer the rods right through the black top if they let loose.

_________________
2006 Liberty Limited CRD, Deep Beryl Green, Yeti tune, Arp studs, new cams, rockers, lifters, TB. "Green Monster"
2005 Liberty Sport CRD, Deep Beryl Green, GDE Hot Tune, ARP studs. "Rocket"
1982 Fiat 124 Spider Convertible. "Fiona"

Please note: My EGT probe was installed in the hottest place I could find, the mouth of the turbo just past the flange where it bolts to the exhaust manifold. Every molecule of exhaust gas had to pass that point to enter the turbo. Apparently, measuring at this point results in about 300 degree higher readings than post-turbo numbers.

While running down the highway, unloaded and not towing... At my usual speed of 75mph, I was reading about 800 degrees continuous. When I stopped or took my foot off the pedal, the temp would rapidly drop (less than 5 seconds) to 500 or so. Temps would come down pretty fast after that while idling, down to the 300 mark within 20 seconds or so.

_________________
Proud supporting vendor of LOST Jeeps
TRAVELING CRD TECH. I come to you!
Need help? Just ask! I've taken it apart more than most.
Email jeep [at] maincomputer [dot] com - BOARD MESSAGING IS BROKEN
Over 225 CRDs currently driving with my valves, timing belt, rockers, or ARP Studs.
Bad noises = REALLY bad things.

geordi,

Thanks..
you're mounting location is the proper place. its what heats up the turbo anything after the turbo the exhaust is cooling. if the turbo adds any restriction to the exhaust gas( pressure increase) as long as the pressure is lower after the turob the gases are cooling. on my cummins is between the head and the turbo..not the turbo outlet..

nice to know these engines cool down quick..might help remove the oil coking from why they die..


it takes minutes for my truck to get to 300f..

-dkenny

_________________
84 BB school bus, DD8.2L turbo ->the transmission died..too expensive to fix..it'll be heading to the scrap yard..4/11)..Bus gone to Scarp 8/23/11
06 Liberty CRD
'99 dodge ram 2500 quad cab, 4x4, 24v
all Biodiesel powered when its warm enough

Toyota Hilux 2.5 and 3.0 both 4cylinder engines
Nissan Navara 2.5 D - 4cylinder
Mitsubishi Pajero 2.8 and 3.2 D both 4cylinder
Kia Sorento 2.5D (VM motori)

These models are sold in europe and non of them throw rods included jeep kj crd .

There is a big number of diesel engines especially in AWD and SUV segment that have big displacement/cylinder.

Here in europe 65% of cars are diesels and only guys that have problems with them are those
that tune them or poorly mainteined them , there is no thrid reason.

So if guys from factory (70 Years history) say that 120kW is optimum power for these engine
call me naive but i belive them.

Libertys are sold since 2001 in europe with crd engines (you can count 3.7 on your fingers)
and there is no problems of that or any other kind that coud be related to bad design or quality.

Ivan, I know tunes push the engine past the limit, some have used them and destroyed a good diesel.

I agree! I will however add a third reason. Running them like a race car!

_________________
05 Liberty CRD Sport with Leather 115k
GDE ECO, No EGR, no FCV, (system gone)
Oil Drain plug P/N 090-039
K&N Air Filter, 2nd gen Fuel filter head
NEW Rockers & lifters
Mobil 1 0w-40
Stant 13519 195 deg inline Thermostat.
0 281 002 845 MAP
Etecno GX3123 7v Glow Plugs
Advance Gold 800CCA Battery
Traded it for a Quality VW TDI

I agree with kjjet. Some diesels can take high RPM's better than others. From what I've seen on this forum, these VM's don't like to be pushed on the upper end.

For example, the old-school Detroit 6-71 (inline 6, 71 cubic inches per cylinder), had a redline of about 2,000 RPM. You could push it (and your luck) to about 2,500 RPM. Big displacement on a diesel=low RPM's. I would consider a 2.8L four cylinder a bigger four-banger and should be treated like so. The 4,000 RPM red-line is a little steep in my opinion. I like to take the safe route and take advantage of the low-end torque at the low RPM's on my diesels. That's what I bought it for!

Billy

anyway to put a rev limiter on these things, except for your foot on the go pedal?

The no load fuel shut off occurs at 4600 rpm on this motor. The only way to get it above that is a run away or if one has the manual version and does a 5 to 2 downshift.

The rpm limit is defined by the rod/crank bearing sizes and rotating mass. Many of the newer automotive diesel engines have redlines above 5000 rpm.

_________________
Providers of wholly developed aftermarket solutions for the KJ CRD.
(248) 977 - 9531

Striperman36,

A rev limit should be able to be done through a tune. I installed a Hahn Racecraft turbo system on my Pontiac Solstice. The tune that was done on my ECM lowered the redline to 6,200 RPM to help keep the motor together. I didn't mind, as there is gobs of available power on the lower end of the RPM range now.

The torque on the CRD is rated at 1,800 RPM. I personally don't feel the need run my CRD on the higher end of the RPM scale with that much torque down low. It rarely sees anything above 3,000 RPM. I do get on it occasionally to blow it out. That's just me though. I've never judged anyone for running anything hard! Just be prepared to pay the consequences if something was to let go! I am prepared with my Solstice. But...parts are much cheaper and readily available for that!!

Billy

the size of the pistons can be determined by the bore.
The speed of the pistons is determined by their stroke.

And yes, while it is large for a 4 banger, it's about on par for a V8.

2.8 x 2 = 5.6

So our little 4 banger diesels have similar piston speeds to a 5.6L V8 @ a given RPM, and slower piston speeds than say a 6.2 at a given RPM.

And there are plenty of manufactures out there making v8 engines rev to 6,000 rpms and beyond.

in terms of the weight, yes, you are correct a typical diesel piston is slightly heavier than a typical gas piston, and this done in turn put more tensile loading on the rod bolts on the exhaust stroke. That being said, there's still way more stress on a GM 6.2L v8 rod bolt @ 6000 rpms than there is on our 2.8 @ 4000.

Rpms isn't really the cause of our rod failures. These motors are bullet proof in Europe, and most importantly they're designed to be used in a boat.

I have a 19.5" boat that does 55 MPH with a 4.3L V6. My motor has over 600 hours on it, and I routinely beat the crap out of it. 4,800 rpms for 10+ minutes at a time.


Diesels typically have lower redlines because of the diminishing results of higher rpms... (and obviously in the case of bigger diesels because they're strokes run into the limits of the speed of the pistons)

more EGT, and less hp than if you upshifted. IE, our motors would make more HP @ 2,500 rpms than they would at 4,500 rpms.

Lack of variable valve timing, and camshaft profiles designed to have maximum volumetric efficiency at low rpms is also another reason.

does anybody make a diesel with a vvalve train that is electrically actuated as opposed to cams? would think if computer controlled variation is done, must be an engine with a much broader powerband.

_________________
2005 Red KJ CRD, TOTALED 12-21-11

2005 Blue KJ Sport CRD, GDE, Magnaflow muffler, Destination AT, Amsoil filters, Fumoto, Timing belt and waterpump @ 99,600, 11 blade nylon fan, 2905 hayden fan clutch, EURO TC




Arguing about whether the glass is half full or half empty misses the point: the bartender cheated you.
Unknown

While electronic solenoid actuated engine valves are being developed, none are in any production
engines. Maybe in about 10 years or so...
You may be thinking about something like a Honda VTEC but those still use camshafts.

_________________
U.S. Army Retired

Getting back to the question: Why so many CRD throw Rods?

Usually rod failure due to lack of libration causing bearing damage from:

1. Using wrong type of oil.
2. Contaminated oil. Due to EGR, to long between oil changes, or dirty air filter.
3. Cold starts, without plugging in heater.
4. Pushing the engine hard, High RPM, Constant RPM changes, Quick acceleration.
5. Using oil flushes. The use of these have been linked to bearing damage.

That’s my take.

_________________
05 Liberty CRD Sport with Leather 115k
GDE ECO, No EGR, no FCV, (system gone)
Oil Drain plug P/N 090-039
K&N Air Filter, 2nd gen Fuel filter head
NEW Rockers & lifters
Mobil 1 0w-40
Stant 13519 195 deg inline Thermostat.
0 281 002 845 MAP
Etecno GX3123 7v Glow Plugs
Advance Gold 800CCA Battery
Traded it for a Quality VW TDI

uuummmhh yes and no - some of them had multiple cam lobes per valve - and the lobe selected depended on oil flow controlled by a solenoid (okay - that was the patent - I don't know if it made it to production)

_________________
2005 CRD
stuff
Skeptic quod gratis asseritur, gratis negatur

There's a few different systems out there but most fall into 2 main categories...

Staged (Honda V-tech, for example, where there are seperate cam lobes for each stage, and a mechanism switches from one to the other, usually at a given RPM)

Continuously variable (most other manufactures. The cam sprocket can advance or retard it's relationship to the camshaft). This has many emmision advantages, and will pretty much be the norm for most new engines.

There are some other exotic systems out there, for example BMW has a variable lift that works so well they no longer need throttle bodies on certain gas engines. You press the gas, the valves open more... This gives them a huge advantage in bottom end torque, because they can get the higher runner velocities.....

Our engine is just a plain-jane dual overhead 4 valve per cylinder ..... no variable valve timing whatsoever. On a diesel, it doesn't offer very many advantages (although, a really exotic system could negate the need for EGR all together, by going "atkins" cycle. As to weather or not that would cause issues with the valve hitting the pistons, that's a whole other story... I believe mazda has some new fancy pants diesels coming out that work that way though....


http://www.mazda.com/mazdaspirit/skyactiv/engine/skyactiv-d.html

The new Mazda could be a game changer. I saw a cutaway of this engine at the Detroit auto show last week. The combustion chamber is quite different from most commonrail engines and the variable lift makes a lot of sense for emissions, fuel economy and cold starting. Looking forward to seeing this engine on the market. Plus the block is good for 400 hp as that is what they are using in the racing circuit this year. The race engine has different turbos, tuning, pistons and fuel system. Fun stuff hopefully!

_________________
Providers of wholly developed aftermarket solutions for the KJ CRD.
(248) 977 - 9531

Yeah...

My wife drives the liberty CRD

I actually drive a 2013 CX5... 2.0L gas.....

nice vehicle... direct injection / non turbo

even with the 6 spd, it's pretty gutless though....

I was thinking about holding off until the diesel came out, but needed something right away....

That and this whole liberty ownership thing hasn't exactly been encouraging for north american non heavy duty diesels...

If it's a "heavy duty" truck, you can get away with murder, emissions wise... anything else, and you're forced to deal with EGR, etc etc.....


mind you though... it's 2013... my liberty is a 2006.... a 6-7 year old Chrysler with head gasket and transmission problems is really nothing new..... it's pretty much been their MO since the 80's, so I guess I shouldn't be surprised....