Even my luck is good somtimes. Cracked bedplate and mainweb

[art leong]

I usually have to manufacture any good luck. But I've had a drop in oil pressure for most of this season. I've changed oil brands, rod bearings, even changed the oil pump, and the gauge. With no change.
I used to have 35 pounds at idle hot, now it dropped to 20 hot. 80 pounds cold, now 60 pounds cold.
I pulled the motor to look at the main bearings. Pulled off the bed plate, and had one bearing stay on the crank (#5). Looked at it and it was worn thru to the copper on the front half of the bearing. I proceed to look at the other bearings and they seem okay. As I push them out and clean and number them. I notice a ridge across the back of the bearing paralel with the crank. I look and sure enough I find a crack in the bedplate main webbing. Upon further inspection I find 2 other cracks in the bedplate main webbing. And a crack in the block main webbing on number 3 (right across the oil feed obviously the cause of the low pressure).
I haven't inspected the crank yet, but it doesn't look bad.
I'm so glad I found this before it puked all over the race track. And I blamed a connecting rod or something else for the catastropy
My question is has any one else had this happen? I'm trying to figure why?

[Sean Marconette]

Art,

What engine?
Sorry to hear the news.

Sean

[art leong]

Originally Posted by Sean Marconette

Art,

What engine?
Sorry to hear the news.

Sean

2.4 liter 4 cylinder Chrysler.
It was actually good news. I'll have to replace the block. But if I had kept running it I'm sure it would have scrapped the whole motor.

[art leong]

Crank checked out perfect.
Now I have to guess what caused the block failure.

[Dennis P Chapman]

Originally Posted by art leong

Crank checked out perfect.
Now I have to guess what caused the block failure.

Just a bad casting not made to do what we do to them.

[ss3011]

How well is the engine balanced ?

[SSDiv6]

Art,

Do you have the EDZ casting engine block?
If you do, that is the standard production block used on the Minivans and regular cars.

The SRT and Turbo cars have the EDV and EDT casting numbers.
Although they say all the blocks are the same, I believe the SRT and turbo blocks to be stronger.

Another option is to use the DCR billet bedplate reinforcement.

http://dcrsrt.com/index.php?_a=product&product_id=162

[art leong]

Originally Posted by SSDiv6

Art,

Do you have the EDZ casting engine block?
If you do, that is the standard production block used on the Minivans and regular cars.

The SRT and Turbo cars have the EDV and EDT casting numbers.
Although they say all the blocks are the same, I believe the SRT and turbo blocks to be stronger.

Another option is to use the DCR billet bedplate reinforcement.

http://dcrsrt.com/index.php?_a=product&product_id=162

I run an early block 99 (caravan/stratus). The oil drainback vent is different on the 2001 and up blocks.
I've talked to several people about the bedplate straps. They all seem to think they are worthless at best. They would be easy to make. You have to machine material off the bedplate to use them. I know of a couple of high HP cars that have broken blocks with them installed.
The balance was checked twice I bought the crank used it was supposed to be balanced but I had it redone (it checked out fine) Plus they just put it on the balance machine this morning.
I have been told that cutting the counterweights off, sometimes leads to bad harmonics

[Mike Taylor 3601]

I was told the same thing years ago,about no counterweights causing problems.They were running chevettes here on dirt track, some of them were cutting counterweights off,I balanced several of them ,they never did run long.
I do know 4.750 stroke BBC will run faster w/ crank w/extra center counterweights,even though it's heavier, than crank w/o extra counterweight. All I can guess is that extra center counterweight must smooth out some of the harmonics and in doing so eliminates some twist/flex in crank,and picks up some power.
Some signs of harmonics are balancer and flywheel mounting areas will show signs walking,galded surfaces, also where main caps meet block,or in your case main bed, will show signs of walking ,main bed may crack like yours before it walks,because of it being held in line w/alignment dowels.
Something else come to mind is a engine that is lugged will break mains/main webbing,Art you have'nt been lugging down the neon so you don't go too quick have you?LOL

Mike Taylor 3601

[SSDiv6]

Originally Posted by art leong

I run an early block 99 (caravan/stratus). The oil drainback vent is different on the 2001 and up blocks.
I've talked to several people about the bedplate straps. They all seem to think they are worthless at best. They would be easy to make. You have to machine material off the bedplate to use them. I know of a couple of high HP cars that have broken blocks with them installed.
The balance was checked twice I bought the crank used it was supposed to be balanced but I had it redone (it checked out fine) Plus they just put it on the balance machine this morning.
I have been told that cutting the counterweights off, sometimes leads to bad harmonics

As regards to the bedplate straps not working, the failures I know that have taken place are on engines running turbos and exceeding 500hp. By the way, I am not implying your engine is not making enough power; I believe that if you use the turbo or SRT block with the straps with your current setup, it will increase the chances of survival.

Also, the reduction of the counterweights will affect the dynamics of the engine, especially on a 4 cylinder. Could you post a picture of the crank?

Another factor to consider is the engine mounting and the stiffness of the mounts. On a FWD, the acceleration and dynamics of the body and transaxle will have and effect on the block. By the way, do you have a filled block?