Ugh did I blow my motor...

[brandon5]

Alright folks here's the deal. I put an rb25 into an 84 bmw. It was my first time driving it on city roads. I took the highway home to go pick up a friend of mine. The road was empty so I did a quick 4th gear pull, at about 180 the motor shut itself off... I pulled the car over to the side of the road and popped the hood. It was really hot and it looked like the intake side, and valve covers were smoking. Tried to turn it over and it made a hateful noise. Decided to check the gas and it was empty (I did a custom fuel setup and didn't have the lever put it). So it seams I ran out of gas at a high rpm. Is it possible I could have leaned the motor out? We got had and it started. But it sounded like it was running off 4 or 5 cylinders. It didn't wanna stay running unless I made it. So I limped it home. I'll be doig a compression test tomorrow, but until then anyone have any ideas? The crankcase vent smells discusting. It's almost a bitter smell, kinda makes you gag. It's also burning oil now.


Sent from my iPhone using Tapatalk

[Skym]

RB25DET engines are known to blow ringlands on the cast factory pistons if run engine too lean (due to knock).

I would do a leak down test on each cylinder. If hear air escaping into sump, ring lands on that cylinder have probably failed.

You can fit a lower compression RB26 bottomend (crank, pistons, conrods) into RB25DET block or RB30 bottomend (more power, torque throughout powerband). Or run forged pistons, thicker headgasket.

[brandon5]

So from what I can see I have a blown head gasket (oil on coolant, coolant in oil). Did a compression test and I got 100 on cylinder one and 90-80 on the rest of them. Not lookin too good right now.


Sent from my iPhone using Tapatalk

[ChezoGTR]

Dunno what the rb25 compression should be at. But I know the rb26 shouldn't be any lower then 130. I'm going to assume something is wrong with your motor. But like I said, I dunno what the compression tolerance is on a rb25


Sent from my SGH-I747M using Tapatalk 2

[brandon5]

Yea something's for sure ******. Just don't have the money to find out. It's weird that cylinder one is 100 and all the other ones are 80 to 90. I'm hoping the headgasket is absolutely blown.


Sent from my iPhone using Tapatalk

[supersayianjim]

26 and 25 and 20 should be 150 for a healthy motor across the board.

[Dragon Humper]

Something is goofy with the VVT.



Jon.

[Skym]

26 and 25 and 20 should be 150 for a healthy motor across the board.

I think anything below 128psi is rebuild time and around 170psi is for a new RB20DET. It can be around 150psi at just under 100,000km.

[brandon5]

Im gonna try a compression test with oil in the cylinder to try and narrow it down. One of the issues will most likely be from when it was over boosting. My controller was hooked up shitty and it peaked at just under 30 for 2 pulls. Im thinking i could have lifted the head and damaged the gasket if not more.

[MattiasJacobs]

Just under 30 psi? Lol, did it sound like the bad news bears were having batting practice under your hood? That sh!t cray.

[brandon5]

It actually sounded pretty sweet considering it probably broke all the things lol.


Sent from my iPhone using Tapatalk