UPDATE- ENGINE FAILURE - 4.7L build from scratch

[doublins]

Good to hear! It's probably running like it should now because all of your valves are working and sealing properly. I'll bet the valve seat damage was already underway when you were done with the break in the first go around. The head work will definitely help wake up a stroker motor too. Just curious.., did you get a chance to put a vacuum gauge on it at idle?

I haven´t with a gauge, but my piggyback infers vacuum from the map voltage, and reads it back to me in whatever units I´d like- I´ll check later and report back in mmHg.

[doublins]

Ok, so even after putting the galley plug back in and driving around for a bit, the oil pressure was lower than I wanted it, so I decided to pull the pan and check the pump-to-block clearance... which looked fine. Then while I was in there I decided to wipe off the cam and check for wear, etc. Looked at the cam bearings and noticed they were OOZED OUT OF THE JOURNALS. Probably happened when I started the engine up the first time without the galley plug in, and would explain the lower than wanted oil pressure since. So, I had to pull the engine again, for the third time in a year, and it´s back to the machine shop for them to fix their mess.

My original engine failure was Jan 3- so with the exception of the couple weeks I got to tool around in it, my jeep has been down for nearly three months. Needless to say I´m pissed.

The only thing that has turned out right in this entire rebuild is the AX-15 and NP231 that I rebuilt myself while the engine was down. If you want something done right....

[6TIME]

Bummer! I've been there..... Were the cam journals checked for proper polish? What were you using to prevent camwalk? Stock pin/spring or other?

[doublins]

Bummer! I've been there..... Were the cam journals checked for proper polish? What were you using to prevent camwalk? Stock pin/spring or other?

I will have them check the roughness avg of the journals when they do teardown- I plan to be there during teardown.

We were using stock pin/spring setup.

[CobraMarty]

You need to have them check the cam stop spring. It sounds like another guys thread where the cam was walking forward and back and taking out the cam bearings. He too thought it was an oil related issue. Took him 4 times to get it right.

[doublins]

You need to have them check the cam stop spring. It sounds like another guys thread where the cam was walking forward and back and taking out the cam bearings. He too thought it was an oil related issue. Took him 4 times to get it right.

This motor didn't even have 200 miles on it- camwalk would do that so quickly?

I am pretty sure that in this specific case, the lack of oil to the cam bearings caused by the shop forgetting to install the front galley plug and me not discovering this until I started the engine to break in the cam, running the engine for 30 seconds until I noticed no oil pressure then shutting it down- the cam bearings were probably wiped right then and there.

That being said, enough people have mentioned camwalk issues, that I am thinking I should look into a solution to camwalk while the motor is apart anyway.

-C

[CobraMarty]

It's a long thread but well worth reading.

http://www.jeepstrokers.com/forum/viewt ... ?f=8&t=444

http://www.jeepstrokers.com/forum/viewt ... ?f=8&t=444

[SilverXJ]

This motor didn't even have 200 miles on it- camwalk would do that so quickly?

It looks like it did it to me.

I am pretty sure that in this specific case, the lack of oil to the cam bearings caused by the shop forgetting to install the front galley plug and me not discovering this until I started the engine to break in the cam, running the engine for 30 seconds until I noticed no oil pressure then shutting it down- the cam bearings were probably wiped right then and there.

I think you are correct that it was the lack of oil pressure that killed the bearings. While you have it apart you may want to put a solid pin in place of the spring and pin. Just in case. Is the machine shop covering this?

[doublins]

This motor didn't even have 200 miles on it- camwalk would do that so quickly?

It looks like it did it to me.

I am pretty sure that in this specific case, the lack of oil to the cam bearings caused by the shop forgetting to install the front galley plug and me not discovering this until I started the engine to break in the cam, running the engine for 30 seconds until I noticed no oil pressure then shutting it down- the cam bearings were probably wiped right then and there.

I think you are correct that it was the lack of oil pressure that killed the bearings. While you have it apart you may want to put a solid pin in place of the spring and pin. Just in case. Is the machine shop covering this?

I read your build thread, and it has me thoroughly depressed- I have no faith that my stroker will ever run right or prove durable enough to turn even 20,000 miles-

As far as covering it- after my first engine failure, I had the shop do a full rebuild and give me back the engine ready to drop in- THEY forgot to install the oil plug and gave me the thing with all the covers on, ready to drop in. I started it up, and was running through my break-in checks when I brought the rpms up to 2000 for breakin then noticed I had no oil pressure- shut it down, found the missing plug- they came to my house and installed it, then I noticed that the engine would never build proper oil pressure, although it was certainly better than it was with the plug missing, lol. While waiting for an HV pump to arrive to ¨fix¨ my oil pressure issue (shop paid for the HV pump), I decided to peek inside the engine and check on the health of the bearings, when I noticed the cam bearings wiped.

Man was I pissed- BUT, I set a new record for engine removal- start to finish, by myself, I had the engine out and on the picker in like 2 1/2 hours. I was a man posessed- I made the shop send a guy to meet me at my house and I dumped the engine straight from the picker into his truck, manifolds, covers, and all- I´m going down there today to tear it down with the guy- I´m sure the cam and lifters are probably gone- lord knows if my rod/main bearings survived, but I´m going to press for a full rebuild- and it damned well better be on their dime- I have photo and email trails of my communications with the shop regarding their screwup and the resulting damage. They´ve seemed intent to do right by me so far, so we´ll see if that trend continues.

Why is it so hard to build a basic, N/A stroker for these engines and get them not to self-destruct? This isn´t rocket science. The chevy guys don´t have these problems

[SilverXJ]

I read your build thread, and it has me thoroughly depressed- I have no faith that my stroker will ever run right or prove durable enough to turn even 20,000 miles-

I wouldn't read into it that much. Its one stroker in many built. And while there have been other recent cam bearing failures yours will most likely fair better than mine.

Why is it so hard to build a basic, N/A stroker for these engines and get them not to self-destruct? This isn´t rocket science. The chevy guys don´t have these problems

I don't know. People have slapped engine together for a long time not even bothering to measure clearances and they ran. On my hand I checked everything, cleaned everything, and did everything possible to make a solid engine and I still had problems.

[CobraMarty]

'checked everything' except cam end play.

Your frustrations and troubles has taught many of us. Sorry it was you, but thank you for your documentation and effort.

[SilverXJ]

'checked everything' except cam end play.

There isn't any end play to check on the stock setup. It should be 0 if it worked correctly.

[doublins]

Well, the machine shop guys feel really bad about everything- they´ve demonstrated good faith and believe we´ll need to do a total teardown/rebuild all over again, on their dime. I think i´m going to ask if I can help out during the entire process

[gonridnu]

Cam bearings are considered a "low load bearing". When compared to the pounding the hydraulic wedge takes on a rod bearing, the cam bearings are seeing almost nothing. The oil system on the 4.0's sends oil to the cam bearings first, mains 2nd, and rods 3rd so they are last in line.

It is logical you would see rod bearing failure before cam bearing failure if the oiling system is inadequate to protect the cam bearings. The few pics I've seen on here of cam bearing failure are useless because it has gone on so long the bearings are completely destroyed and beyond inspection.

If the rod bearings look ok and there is cam bearing failure it is related to either inadequate valvetrain clearance (as in something binding at full lift) or improper camshaft to bearing fit. it is not uncommon to need to massage cam bearings in order to get a good feel when the cam rotates, which should be fairly easily by hand. I'll also go with the surface finish of the cam itself as described in a thread here. Although I have never run into that problem, I am keeping an eye out on everything I build.

All I know is if the rod bearings don't look just as bad it ain't oil related....

[gonridnu]

Just realized you have aluminum rockers. Take an intake and an exhaust rocker down to the machine shop and have them press the bearings out and measure the bearing bore on their rod hone gauge.

If there has been any valvetrain interference it will show as a distorted bore in the rocker arm. It should be round within .001" or so depending on manufacturer. The aluminum arm will distort in the bearing bore area if there is retainer to guide, or piston to valve, or any other similar interference that could be putting undue stresses on the cam bearings.