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post #1 of (permalink) Old 04-30-2007, 02:51 PM Thread Starter
JCP
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4.0 with blower failure

About 18 months or 2 years ago I sold a bully a clean 99 tj with manual trans and 4.0 six. with only about 35K milage. It ran fine. About a year ago he put on a supercharger and the onther day (55k miles) had a catastrofic failure with the number six piston (closest to fire wall) goin through the block. The driver was traveling at highway speeds and buy reported hear noise that he ingnored for 10 to 20 minutes. Don't know if he noticed or checked for lost oil presure before failure (at least he hasn't admitted it). I would have thought is might be rod knock with subsequent bearing failure and seizure. But why the piston through the block?

The first and obvious question is did the blower contrubute. (unknown bost)The were no know oiling problems. I doubt he (or his son who was the usual driver) would have recognized subtle signs of impending failure, eg piston slap.

What do you think the most likley cause of failure was? And in putting in a new (Mopar) crate engine is the any thing one should do as a prvenative measure, e.g high volume oil pump or something?

Any Insight?

67 half cab Jeepster
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post #2 of (permalink) Old 04-30-2007, 03:11 PM
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IMHO if they are dumb enough to put a Blower on a Jeep, they are dumb enough to over rev, under oil, and just plain abuse it.

I sure hope you didn't give him some sort of warranty.

I could hear the conversation if I was in your shoes:

"You sold me a lemon, the # 6 piston is toast after 20k Mi"
"Wow, really, what happened?"
"nothing, just driving 55mph on the freeway, obeying all the traffic laws"
"Ah, hmm, did you upgrade anything on the Jeep after I sold it to you?"
"Just one small upgrade, I had a supercharger installed"
*Click*

Scott
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"He brought me up out of the pit of destruction, out of the miry clay, And He set my feet upon a rock making my footsteps firm."
-Psalm 40:2
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post #3 of (permalink) Old 04-30-2007, 03:31 PM
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My guess would be that the supercharger caused too much cylinder pressure and blew a head gasket. Water got in the cylinder and the piston tried to compress it.

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post #4 of (permalink) Old 04-30-2007, 03:38 PM
 
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OOps, got the wrong message on this post!

Having worked for BDS (Blower Drive Service) I can tell you a few things about supercharged engines, if you want to know...

Last edited by Junk Yard Genius; 04-30-2007 at 03:55 PM.
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post #5 of (permalink) Old 04-30-2007, 04:20 PM
 
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What a coincidence;

About 18 months or 2 years ago I bought from a buddy a clean 99 tj with manual trans and 4.0 six. with only about 35K milage. It ran fine. About a year ago I put on a supercharger and the other day (55k miles) had a catastrophic failure with the number six piston (closest to fire wall) going through the block. My son was traveling at highway speeds and tells me he heard a noise that he thought was a broken belt, stopped and check but could not find the source then proceeded to drive for 10 to 20 minutes. He did check his gauges and all looked good before failure.

I would have thought is might be rod knock with subsequent bearing failure and seizure. But why the piston through the block?

Oh, wait, this is the same incident...

This is my sons baby and he treats it that way, this is not to say that he has not done something without realizing it though.

Hey thor, never once did I accuse or ever think JCP sold me a bill of goods or did I try to blame him... So, smart a$$, explain to me why I was dumb enough to have put on the supercharger.

Junk Yard, I would like to learn as much as I can about blowers, please enlighten me.

CJ7Taz, The radiator is still full of coolant and oil free. The dip stick still shows well inside the safe range. If it blew a head gasket wouldn't the two fluids be mixed.

As JCP mentioned above, what can I do to prevent this from happening again; yes I will be reinstalling the supercharger.
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post #6 of (permalink) Old 04-30-2007, 04:21 PM
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detonation kills supercharged engines.....were they trying to save money with low octane gas since prices are high?

anyone know if the stock 4.0L has cast pistons? those really dont like detonation....it could break up a piston, sending peices of it fly'n

do i think the charger had a hand in killing the engine...um yea. hard to tell exactly how though unless you inspect parts....theres a long list of possible causes.

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post #7 of (permalink) Old 04-30-2007, 04:46 PM
 
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Quote:
Originally Posted by JeepnGreg View Post
detonation kills supercharged engines.....were they trying to save money with low octane gas since prices are high?

anyone know if the stock 4.0L has cast pistons? those really dont like detonation....it could break up a piston, sending peices of it fly'n

do i think the charger had a hand in killing the engine...um yea. hard to tell exactly how though unless you inspect parts....theres a long list of possible causes.
I assure you my son doesn't try to save money on gas by buying anything but premium since I'm the one that pays his gas bill. Damn spoiled kids...
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post #8 of (permalink) Old 04-30-2007, 04:47 PM
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Quote:
Hey thor, never once did I accuse or ever think JCP sold me a bill of goods or did I try to blame him... So, smart a$$, explain to me why I was dumb enough to have put on the supercharger.
Oh, I am sorry, I want all my kids to own a supercharger on a vehicle that stock, will flip at 55 (I dunno TJs may be a little better, but that was YJs). Works well on the rocks, by the way, Boo Hoo you aptly choose your name.

Sorry, I love superchargers, on the right application IMHO.

I think on a Jeep, it is a joke. Sorry to tell you that. Did you get a free lowering kit with it too?



Quote:
I assure you my son doesn't try to save money on gas by buying anything but premium since I'm the one that pays his gas bill. Damn spoiled kids...
I apologize, I didn't see your post before I posted back. Now I know you are one of THOSE dads, we see allot of those around here, and their spoiled rotten, "the world owes us" kids.

Just judging you on the information given, though it looks like a duck to me!

Oh yeah...
*Click*

Scott
1985 CJ7 T.H.O.R

"He brought me up out of the pit of destruction, out of the miry clay, And He set my feet upon a rock making my footsteps firm."
-Psalm 40:2

Last edited by thorjeep; 04-30-2007 at 05:08 PM.
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post #9 of (permalink) Old 04-30-2007, 04:49 PM
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Quote:
Originally Posted by Boo Who View Post
CJ7Taz, The radiator is still full of coolant and oil free. The dip stick still shows well inside the safe range. If it blew a head gasket wouldn't the two fluids be mixed.
Quote:
Originally Posted by Boo Who View Post
... and the other day (55k miles) had a catastrophic failure with the number six piston (closest to fire wall) going through the block.
Are you telling me that a piston went through a cylinder wall and there is no water in the oil? Or did you word that carefully so that I would make that assumption? I didnít.

NO, you donít have to get oil in the water with a blown head gasket. You may not notice much water in the oil.



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Originally Posted by Boo Who View Post
As JCP mentioned above, what can I do to prevent this from happening again; yes I will be reinstalling the supercharger.
Then youíd better pay the money to have an engine built to run supercharged.

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post #10 of (permalink) Old 04-30-2007, 06:11 PM
 
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To start with, there is no such thing as 'Screwing On A Blower' and driving off.
This is a myth that ranks right up there with HEI ignitions, cars running on moonshine, factory differentials being 4 wheel drive and Rolls Royce offering a life time warranty.

There is much you need to do in preparation for a supercharger, even a little street charger...
The bottom end of the engine should be built as solidly as you can afford.

First thing I can think of is using a good head gasket.
Fel-Pro makes a stainless steel shim 'O' ring head gasket that will hold back boost up to about 14 psig.
After that you will have to 'O' ring heads to keep the boost pressure in.

Secondly, I'm not crazy about the unsupported cylinder walls in the 4.0 engine.
With no top deck, the cylinders may cool more evenly, but there is much less support, and Siamese cylinders are a problem all of their own!
(remember the SBC 400 and it's problems?)

Steel crank is nice, but not absolutely necessary if you stay below 7 PSIG boost.
Above 7 PSIG it's a crap shoot if your cast crank is going to live.
We have nodular iron small block Ford cranks living on 750 HP/ 735 Lb Ft. Torque engines, but don't try that with a cast SBC crank!
I've never supercharged a 4.0 Chrysler engine, but if I were you, I wouldn't experiment with MY engine...

Steel rods are a requirement as far as I'm concerned.
Cast iron and aluminum rods have problems with detonation, which a blown engine is certainly going to produce at one time or another.

A premium rod/main bearing, like Clevite 77 bearings, are a must.
Cheap bearings will delaminate and/or squish out of the contact areas.

If you can get around it, don't use a bushed rod.
(In some Fords you may not have a choice...)
the bronze bushing tends to hammer out sideways (diagonal) and allow the wrist pin/piston to cock in the bore.

Forged pistons are a MUST! You get what you pay for, and good forged pistons will be an insurance policy that is worth every cent.
Cheap cast pistons, and even the 'Hypereutectic' pistons won't live above about 5 psi boost, even if you manage to eliminate nearly all the detonation.

You need a short overlap cam shaft.
Factory cams with long over lap (so they send a good vacuum signal) won't work worth a darn and should be avoided at all costs!
Since you are making all your power down low in the RPM range, don't worry about fancy cams like roller lifter cams and such... It's a waste of time and money.
Stock type lifters, or even a lifter with some delay built in will work best.

Push rods, rockers, valve springs, ect. can all be stock below 7 PSIG boost.
More than 7 PSIG boost and you will have to step up the spring seat pressure on the intake valves to get and keep them closed.

Don't worry about high RPM anything, since a supercharger makes it's power low in the RPM range, you don't need the super high priced, super high RPM stuff...
No super expensive balancers, no roller cam with astronomical seat pressure springs, no rev kit for the roller cam, no expensive porting/polishing of the intake or head runners...

One thing you CAN do if you want to...
Clean out/up the pocket and runner of the EXHAUST valve.
With positive pressure on the intake side, this thing is going to get a breath, but to exhale can be a problem with some heads make for smog/emissions operations.
We often open up the exhaust valve, trim away the excesses in the exhaust port and runner, and put a good set of long tube headers on it.
Virtually nothing is done to the intake side except pocket clean up and port matching.

You will need a PREMIUM TRUE DOUBLE ROLLER TIMING SET.
None of the so called 'Roller' timing sets from china...
The timing chain and sprockets are going to take a beating from a supercharged engine, and you REALLY don't want the cam/ignition timing to be off!

Another thing you will need is an MSD 6 series ignition module.
Higher pressures will play hell with the stock ignition, so go ahead and get an MSD now.

Supercharged engines like a LOT of timing!
If you pipes are glowing at idle, you don't have near enough timing!
Use one of the cheap infrared temp guns on the exhaust tubes right out side the head,
(usually at the first bend is a good place)
And play with the timing.
Add some timing and the temp should go down considerably.

Lots of advance REAL QUICK.
You should be looking at 35 to 45 total advance, and all of it in by about 1,300 RPM.

Top end of the operating RPM range you want to knock back timing a little.
MSD makes a timing control module that plugs into the MSD 6 series and it will let you program some retard at higher RPM.

Questions, or shall I go on?
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