2nd Gen R56 Cooper S Most liked posts in thread: Default PSI Readings

Good advice a wet compression test would have saved you a load of grief. Since you flooded your car with enough gas to wash the oil off the cylinders that gas is now in your oil & it is now diluted. Your 0w40 may be something else now. Change your oil....

Great first post, welcome to M/A

 

But three times on this forum alone? That's a little overkill.

Believe me, I've been working on cars for over thirty years, there are too many variables to have a single default compression test number for any engine. Your own car's numbers will change from day to day.

Tell us what numbers you are getting, what is the problem you are trying to fix?

If you think your numbers are low, squirt a little engine oil into the cylinder and retry the compression test, if your pressure comes up significantly, your rings aren't sealing well.

Dave

 

You seem to have a lot of issues with your MINI.... We give you suggestions, but you don't seem to followup with feedback... One of the things that was suggested was to buy a Bentley Repair Manual.... It goes into great depth on how your MINI works... Did you buy one yet?

Don't forget.... you are the closest inspector to you MINI.... We are possibly on the other side of the world trying to analyse where you are going with your questions...

OK..... Gotta ask.... Wuts "Polyphony"????

 

I own a 2007 MCS and my compression test results are below and is considered great for 53k miles, I have assumed that maybe a brand new 07-09 MCS could be around 160 psi after break-in. I'm just going off what others are reporting with similar mileage. So here is the best guess you're going to get, not every engine is the same off the assembly line.


1. 155 psi
2. 153 psi
3. 154 psi
4. 156 psi

 

My car just returned from the dealer shop and it's worth sharing the story so others may benefit. I have a 2008 R56 with 80K miles. The car was working fine one day and the next it wouldn't start. It would crank but not fire. The spark looked good and the plugs were dry when removed. Without a compression tool handy, I mistakenly made the assumption the compression was ok and assumed it was a fuel problem. The LPFP was pumping fuel but stopped after checking for low pressure fuel going to the HPFP. I was hoping the HPFP was the culprit due to its high historical failure rate and dry plugs. We had the car towed to the dealer for what we hoped was a warranty repair. I received a call from the shop informing me the compression on all 4 cylinders was down around 20 psi. The mechanic felt the car probably over heated and the head was warped. The water pump was leaking yet the coolant level was fine but he he attributed that to the problem. Given the dealer's rates for service, the estimate for a new engine replacement(~7.5K) was slighter more in cost than repairing the low compression problem. It was terrible news so I stopped by the shop to speak with the mechanic. In his defense, he said he didn't know the cause for sure until he took the head off the engine and inspected it. He said it was an 11 hr job and that was expensive by itself. Sad day and reluctantly agreed to a new engine. Two days later I called checking on the status and they told me the car was running. They called the mini technical support hot-line and my car's symptom was similar to another they had recently looked at and it was due to a flooded engine. The mechanic explained it as the gas flooding the engine caused the oil to clear off the cylinder walls which impacted the overall compression in all the cylinders. He was advised to fog the engine it it worked. The compression was restored. Imagine how relieved I was yet frustrated at the same time. As for root cause of the flooding, he thought the battery may have been low. The battery was replaced in the spring with Sears Gold battery and apparently should have been "registered in the car's computer to optimize the charging algorithm." It was another learning experience. He thought a low battery could allow for the injectors to fire but the car may not have cranked over enough to start and after a few tries, the engine would flood causing the problem. They changed the water pump and updated the DME for the battery characteristics. It's been home now for two days and the car has started each day. I want to trust the dealer's mechanic but still spinning my head over the experience. Bottom line, if you have low compression try spraying some fogging oil in the cylinders and see what happens. Anyone else see experience this type of problem?

 

Soo-- you are going to keep asking this question until you get an answer that doesn't exist?

http://www.motoringalliance.com/forums/cooper-s/17741-need-help-performing-compression-test-2.html

Dave

 

And on NAM.....
Boy...asking the same folks the same question....
and expecting to get a different question....I think that is the DEFINITION of INSANITY!!
Sure....we are the "friendly MINI site", but common.....I don't think you can fault us for wondering WHAT is up.....

 

Don't have an answer but I'll give you a bump.

 

Great advice to change the oil quickly due to the potential of gas mixing with it. I usually change it around 5k and it's almost due anyway. Appreciate that.

 

My results are quite different after using BG's Engine Performance Restoration added to my oil and revving engine at 1500 rpms for 10 minutes before oil change. It cleans around the rings and cross hatches.

1. 165 psi
2. 165 psi
3. 170 psi
4. 165 psi