Rough running 4.8is

[panchosouth]

Photos from the shop- Lots of sludge, as you can see, and possible oil starvation on the top end. Now having a compression test to check the bottom end…..To tired to discuss more, will be speaking with the SM again tomorrow.

More later.

[e30cabrio]

Wow, that is a mess. Sorry.

[SlickGT1]

Holy shit. Have you done an oil change since you bought it.

[panchosouth]

Quick question- I can't remember where I read this here, but I remember someone suggesting a shop in the south somewhere that could rebuild the engine and bump up the horsepower…I'm of a mind to have them pull the engine and ship it somewhere….Anyone remember anyone talking about a shop like this…? Maybe in Dealer Blew my Engine…?

E30- Thanks. We bit of a bummer.

[panchosouth]

Slick- As discussed at the beginning of the thread, pretty extensive efforts to flush engine out as carbon build up was thought to be an issue- this included a hot oil engine flush. To be more specific, yes, a number of times.

[SlickGT1]

I think you are thinking of VAC motorsports. Call them and find out who they recommend, or if they even have a shop in your area. Are you sure you need a rebuild. Maybe all you need is a serious cleaning of the inside. Specifically the valve covers. They have a lot of passageways that collect sludge.

[bcredliner]

Not a pretty sight! Sorry.

[TiAgX5]

VAC Motorsport is where you need to go. They can pull well over 600 hp from the M62 engine without forced induction.

No idea what they can do with the N62 4.8.

[Doru]

Originally Posted by panchosouth

Photos from the shop- Lots of sludge, as you can see, and possible oil starvation on the top end. Now having a compression test to check the bottom end…..To tired to discuss more, will be speaking with the SM again tomorrow.

More later.

I looked at a vid that talks about failing oil return check valves. They say these can fail either in open position (the plastic end valve crumbles) and you have the "low oil pressure" light, or they can stick close - if this happens, I suppose you could have oil starvation. I posted the vid in this post. Could this be the issue on your engine?

[panchosouth]

Good afternoon Mr. Hogan,

I reviewed the service history in the back of the car and noticed the misfire situation has been there since you purchased the vehicle.
I was surprised to see the hot engine flush had been done with the amount of buildup in the motor. The issue at cylinder #5 is still there along with
faults at several other cylinders.

We have had a chance to perform both a leak down test and a compression test. Unfortunately the compression
test has come back with some less than positive results.

After running the compression test several times there are some significant differences between the cylinders.

1 – 90 psi
2 – 110 psi
3 – 110 psi
4 – 130 psi
5 – 150 psi
6 – 150 psi
7 – 120 psi
8 – 130 psi

While replacement of the heads could potentially correct the concern, it may end up being a problem in the bottom end which
would probably make engine replacement the most cost effective method of repair.

I can try to find a used motor, which would be cheaper than the new heads.

Let me know your thoughts, and if you have any questions please don’t hesitate to let me know.

Kind regards,


David Young
Service Manager
Otto’s BMW Centre