Question for all of you.

I recently did a bunch of work on my '05 MCS. Just before I had the car apart, I noticed something strange happen where my oil pressure light would come on when I stopped the car with my foot on the clutch and with the brake pressed. The pressure would drop to roughly around 10 PSI and then drop right to 0. I would press the gas a tad, and oil light gone. I figured, I might be a little low and when I was doing the work, I was changing the oil anyway. I changed the oil, did my work, which consisted of a clutch, hitting all of the areas the mini coopers leak oil from (which mine were leaking) and some suspension bits sense I had the subframe out. I put everything back together and noticed the same problem having. So far I have done the following, but it seems pretty strange.

1. Took oil filter out, and reseated everything. I am using an OEM filter.
2. The oil sender had oil on it, so it seemed like it was leaking and getting into the wiring. I changed that out and bolted the new one on last night.

I noticed it again when I was in stop and go today. The oil pressure seemed fine while I was driving with no issues. Once the car went to idle, the PSI would drop down and the tach would read under 1k and the oil pressure would drop to 0 and the light would come on. No change to how the motor ran, didnt notice any idle changes as far as it stalling or anything. I rev the motor up just a bit and it's back off. I got home, and parked it, then had to run out less than 5 minutes later and the problem didn't exist at all. I didnt drive that far, but you would think the car was warmed up so it would have had the same problem.

Any Thoughts on this one? I run Royal Purple 5w30, and have for years. Car has about 127k on it and has always run fine, engine wise, up until now. I know I had some suggestions and next steps of a Filter housing, but has this happened to anyone? I would rather not drop the $ on the oil filter housing and it not be that.

Michael

 

I would plumb a mechanical oil pressure gauge before I spent the money on an oil filter housing. Get the actual numbers that can't be disarrayed by computers.

The bypass valve and spring were intact inside the filter capsule right? I've seen them broken before causing constant oil bypass and low pressure.

It's not uncommon to see low single digit oil pressure at idle, but it will go up as you raise the revs as the pump is a gerotor driven directly off the crank.

For the bads:
It could be main bearing clearance issues
Worn oil pump
Above stated broken bypass spring/valve

But all of these are rare occurrences, and I have yet to see main bearings bad enough to cause oil pressure issues in these cars.

 

Thanks for the reply. I do have an oil pressure gauge in the car as it was configured from the factory. While I am driving the pressure is fine. And most of the time before the car warms up, when it is sitting at idle, it's fine as well. It will stay right around that 10psi mark. The spring and bypass valve seem to be in tact with no issues.

Are there any tests I can do to narrow it down? This may require some guidance on telling me what might need to be changed so I can change the parts. Would it be worth having the dealer look at it and pay the fee for them to provide me with the verdict? I have no issues changing the oil pump or even the filter housing, but both of those can be pretty pricey and it would be nice to narrow it down for certainty what it is.

 

I believe the oil warning light activates in response to the oil pressure switch on the side of the oil housing, and your oil pressure gauge has a seperate sender. Since they are behaving consistently with each other, I think it is likely that the oil pressure is dropping when the gauge says so.

As to why... No great ideas. One thing I would check is whether you have the correct oil filter - are you aware that the early R53 use a filter without a cage (the housing should have a cage, which sometimes get misplaced) and later R53 use a filter with a plastic cage built in. From your year, your car should use the ones with the cage built in - do you look for it when you change the filter? The oil pump is integrated into the front timing cover. There are some small chanels in it that could get occluded. Any chance something got in there? Like the end of a broken dipstick? The tamper-proof seal from a bottle of oil?

 

If you have a mechanical gauge wired in and pressures check out fine then there is an electrical issue with either the sender or the wiring for the sender.

There is only one oil pressure sender on the car, I prefer the oil pressure gauge be tapped in at the sender with a Craven Tapless adapter as opposed to other solutions.

 

Okay, let me just follow what you are saying. I am assuming the stock oil pressure gauge in the car is fed from the electrical connection on the oil pressure sender and that feeds the oil pressure idiot light as well? Are you suggesting hooking up a mechanical gauge with the Craven adaptor that goes right before the oil pressure sender to bypass the electrical feed?

I took a look at Real OEM site to get an idea of what parts / pieces make up the oil filter housing. Everything seems to be in tact, with exception to the part in the image attached. Is this the cage mentioned above? I've had my car for 10 years, and the first couple of oil changes were done by the dealer, the rest by me, maybe one or two shops along the way. If that part was in there, I probably misplaced it or it came out in the oil filter when I changed the oil for the first time. Is this a replaceable part without buying the whole cage? I can't imagine this is causing the issue I am having because this is the first I noticed it wasn't there. What does that part do?

It's a 2004 and the Prod month is 10/2004

I appreciate everyone's input. Hopefully I can get to the bottom of it. I plan on getting back on it once I am home from vacation.

Michael

 

I hope Nkfry can confirm what he/she/it/they (the world is getting complicated) meant.

I believe you should have 1 oil pressure sender and still also have the oil pressure switch that activates the light at very low oil pressure (but doesn't read out pressure). If this is the case, the fact the light comes on when the pressure gauge is reading low means the two sensors agree and pressure really is low.

If the oil pressure switch has been replaced by the sender, and there is only one unit total, then a bad sender (wiring, etc) remains a possibility.

 

About the cage - it keeps the oil filter from collapsing. No, its not available, BUT, read on.

The problem is that early cars have this cage built into the housing and the filters are just a paper sleeve with no mechanical strength. If the cage is lost, or an early filter put on a later car, the oil will bypass the filter (this is the best case) or the deformed filter will jam something and restrict flow. I would be worried about this second case here.

The filters for a 2005 should come with the cage built into the filter (this is what you should be checking every time you get a filter from the dealer) and I think your housing would be the newer style with no cage built into the housing. Mini Mania lists the change over date as 07/2004. There are pictures of the housings here if you want to look (no endorsement implied) - http://new.minimania.com/MINI__02_04...roblem___Hints

 

Thanks, I did some research last night after the post and found the article on Mini Mania stating that the cage was removed after 07/2004. I was worried about it, because I thought I misplaced it. But, good point on making sure the filter is correct, I will pull it out when I am back in town to see if I got the right one. Hoping it's something that simple, but doubt it. I see maybe the previous filter collapsing, but I did just change it and it has maybe 200 miles on it.

I guess besides the oil pressure gauge, is there any way to test the oil pump? I may take it to the dealer, pay the fee for them to tell me what I need to change it, then change it myself. Seems like a better route then to pay to add another oil pressure gauge just to validate that the stock gauge is working, then still not know what the root cause is.

Anyone know of any good Mini Mechanics in the phoenix AZ area? I will post a resolution if one is found...

 

The official way to test it is to unthread the oil pressure switch and attach a mechanical pressure gauge (~ $35, such as ATD-5550) and watch the gauge under various conditions. Cheaper than the dealer fee...

 

This happened to me
And the oil filter was the culprit. Maybe it's in backwards if you have an oem filter? It seems as if when the oil filter is being bypassed somehow, this happens. Otherwise good luck! This issue drove me crazy, first and last time I ever let someone change my oil.

 

Well, I figured I would let everyone know where I am with this issue. I got back from some time off so the car has been sitting for about 2 weeks. I went through and did the following.

1. I took the filter back out to check everything. Luckily, I put it in the right way but I did check it and it's the right oil filter and reseated it. I also checked the inside of the oil filter housing. Seems like everything is in there an in tact.

2. One of the things I changed was the oil pressure sender unit, which had been leaking. This was causing the connector on the back of the sender to seem a little wet because of the oil.

I don't know if the sensor wiring ended up drying up, creating a better contact but the oil pressure light has not come back on in the past two days of driving the car. I was sitting in stop and go traffic on the way home from work and I took the car for a long drive today. The oil pressure is sitting where it has when the car warms up. It was happening after the car warmed up, and I thought when the oil thinned out. But, I have not been able to get this replicated. So, I think this may have just been an electrical issue. If there's oil pressure there, should be good right?

Unfortunately, while I was driving the car today, I think the CAT split or broke, because now I have a really loud exhaust leak. A really loud one and it seems to be air coming out of the bottom of the CAT. No visible holes, but now I need to research what to do there now... Crazy!








About a few minutes into my drive






After car warmed up driving about 40 minutes. This is when I came to a stop and the car was in Neutral, which is when it would normally drop and the light would come on.

 

You'll need to take the header down out of the car, cut about 3/4" off the bellmouth around the primary cat and weld it back together. It's a quick easy job if you have access to a welder or know someone who does. They usually crack either at the bottom of the primary cat or at the entry to the secondary cat, either of which is a quick repair.

 

Sorry for the large photos...

First off, holy cow this part is expensive... Called the dealer to get a price, almost $2k? Highway Robbery... Not that I would go the dealer route, but wanted to see.

I took the car down to a local shop because I don't have welding tools (unfortunately). They are going to take it down and weld the seam up where it separated. It was a clean separation so they are going to cut the heat shield back just a tad to get a clean weld on it. They tested the CAT to make sure it was still working so hopefully it will last for a little while, at least. Otherwise, I will look at an aftermarket piece like the Flashpoint Mk1 or some similar OE replacement. With this repair, an potentially having to replace with an aftermarket, I am still way under what this shop quoted me and the dealers price.

I think (hope) the oil pressure issue is resolved. Will keep an eye on it to see if the light comes back on.

Certainly appreciate everyone's help in troubleshooting. Great to have resources for validating these things that happen to our cars.



Michael

 

Thanks for the info here. I'm new to the forum. I am also having this issue, but with a twist...


I have an 05 MCS with factory pressure gauge. Hmmm, where to begin...


Well I think I'll abridge it. Was almost certain I had an indication issue. Light and pressure drop would happen in rain and while cruising steady on highway. No correlation to engine RPM, no other indication of low pressure or level.


Recently started correlating with engine oil warm and dropping to idle. Basically same as described in thread.


At this point I changed the sensor at the housing, the oil with same Castrol 10W-40 synthetic I've used for past 50k miles, and a Wix filter with cage built into filter. I've never had an issue with any of the filters and I admit, I've thrown Wix, OEM and Mann in at any given point. I've also never really had an excessive consumption issue.


When changing oil, checked bypass plunger and seemed fine, but didn't scrutinize as I thought the switch was my fix.


When first started car, everything seemed fine. Drove to work (110 miles) on a rainy Tuesday morning and had frequent drops the whole way in.


OK, this is getting long-winded. Hopefully you get the point. I'm wondering if I can trace this to a problem in the wiring harness? If I have a weak connection or corrosion, maybe the electrical signal isn't properly getting to gauge. Additionally if resistance drops when mechanically read pressure drops at switch...could my electrical signal to the gauge be mimicking an oil pressure being low due to not enough voltage getting to gauge? Does that make sense?


Help!

 

When mine had the issue described in this thread, the oil pressure at the oil sender port was actually 0 at idle...probably shouldn't have driven it at all.

 

I assume you verified that with a separate gauge then?

 

Check your engine harness wiring to the oil pressure sitch
Btw chrono pack cars do not have an oil pressure sensor
The chrono pack displays a calculated pressure not a measured one
When the oil pressure switch or its wiring malfunctions the chrono pack shows 0 psi

 

Chris, ok thanks for the clarification on that. Can you explain how it's calculated? This may point me somewhere. I assumed the switch operated by oil pressure acting on some sort of sprung plunger that varied resistance to ground as it moved?


Can you help me with where to dig up a diagram showing the wire routes and colors?

 

Yes.

 

Scary. Well I really hope that's not my situation. I would think by now it would mean serious engine damage. When I pulled the oil drain there was no debris. In fact oil still looked pretty clean as it was before scheduled change. I'll update what I find. Drove home today with no issues. Crossing my fingers for wiring :/

 

oil pumps are designed for the engine warmed up at idle, thats the hardest point to maintain as all clearances are at the largest and the engine speed and pump is lowest. varaible pumps help a bit even get ECU input. the mechanical gauge will give the most reliable readings. If the oil pressure is low work back through the system from the filter housing to the pump. Low pressure is not the issue but low flow or zero pressure is

 

Its calculated from coolant temperature, engine speed and engine run time
Link to a full electrical manual

http://www.newminiclub.nl/diy/wiring_r53.pdf