Hi,
So I just got her back from NW MINI. All systems go but they told me it has low compression in cylinder 4. Service advisor suggested I put some fuel injector cleaner in it next fill-up (I did) because it's probably just gunked up.
That's what he said.
Questions, concerns, comments?

I should've asked if they did a leakdown test.. I'll call in the morning.

 

Not sure what the relationship is between a clogged fuel injector and low cylinder compression. One doesn't have anything to do with the other.
The service advisor doesn't sound too 'techy'. Leakdown test. Get it or do it yourself.
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Are you spark plugs torqued to spec? I don't think they could back out on thier own. If it is not the plug, then the problem is either the rings, or the head gasket, both of which would be expensive to fix.

 

Could also be a valve guide or seal too. Maybe even a stuck valve. How many miles on the MINI? Whats the driving style of it's owner?

 

I wouldn't be worried about the gasket...you'd be getting shitty oil if that were the case.

Check valves and rings. Compression and leakdown.

- Matt

 

63,000. I bought it last week..

 

Is the valve cover gasket reusable? I mean if I pull it to check the valves. Sorry, new to Minis..

 

what are the numbers, by cylinder?

 

225 225 230 190
_1___2___3__4

 

Considering how relatively inexpensive gaskets are, I don't re-use.

I don't imagine you'd have an issue with the valve cover gasket specifically though...the loads/pressures on it aren't high.

- Matt

*Edit* Gasket is Part No. 11121485838, cost $12.25 @ PelicanParts.com

 

thanks Matt.. and to everyone who's posted!

I spoke with the service rep this morning and he said they pulled the valve cover and everything looked ok with #4, no broken springs or obvious damage. They did not do a leakdown test but he said that they see a lot of MINIs with low compression in one cylinder & 9 times out of 10 it's carbon buildup on the exhaust valve and is fixed by a good fuel system cleaner. He said at worst it's a burnt valve...
He told me not to worry about it, that they wouldn't have let me drive it if they thought it was something more serious and he will stand by their inspection should something more destructive occur. Said to run a cleaner thru and if I get a check engine light anytime soon to immediately come in to check compression.

 

I don't think it could be a plug since the compression test is done with the plugs out?

 

Keep us posted glad it does not sound too harmful...

I had a fluttering sound in the #4, but after my last oil change everything has been perfect...\

No idea why...

 

if you have any leverage (30 day warranty, that sort of thing) i'd see what could be done

190 vs 230 is a damned significant loss of compression

not disagreeing with the SA, but if the exhaust valve is not sealing due to carbon then
1. a wet test should pump the same, does it? if not it's rings not valves
2. the area around the supposed exhaust valve carbon deposit will leak exhaust gasses during the power stroke, which will make a perennial hot spot that will cause further damage over time -- $$
3. that raises the question of why the carbon is there too does it not?

will the seller accept any liability for the problem? pulling the head now will probably be cheaper than pulling it later...

 

thanks Left Ear, love that show

I do have a 30 day warranty, trying to negotiate a lower selling price right now & they want their (Barrier) service dept to look at it.
When I bought it it was bone dry (coolant) & had a bad water pump, 2 bald tires, 3rd with a nail in it. I didn't know about the engine issues, but I knew it was in a front end collision (CarFax) and the alignment was waaay out plus missing some bolts. So I have some $$ invested already!!
My game plan is to run out the fuel that's in there - I put in some 76 brand fuel cleaner in yesterday... then I'll run thru a tank with a bottle of Max44 Complete Fuel System Cleaner (SA recommended this brand), then take it in to Barrier for a compression test (on their $), & go from there. Can't seem to find any Max44 around here though...

 

No problem...BTW...if you are planning on modding the hell out of the car now would be the time...once you get this solved(make sure you are not screwing anything up by adding to the problem)/before cracking open the head...think about a new one( www.revolutionmini.com ) along with other parts that could be done at this time...cam, pistons, etc...all depends on what you want out of it

I know you may not have these crazy mods planned, not everyone does, but if you are thinking about them in the near future do them now

 

I shouldn't even be thinking about this right now but what kind of performance gains could be had from the head alone?

 

your advisor is probably thinking you've got a seized ring . # 4 runs hot . i'm told and was the worst on mine when (it) happened . the injector cleaner probably won't loosen the ring but some stuff on the market may . like marvel mystery oil . you could try seafoam in the oil . it is one of seafoams ' recommendations .

 

Ok, so I don't want to have more additives in my fuel than fuel!!

Wondering if I should use the Max44 in my fuel or the Marvel... or maybe Marvel in the crankcase & Max44 in the fuel... hmm..

 

In your area, Schuck's, Autozone, or B&B Auto parts will carry Seafoam, Lucas, or DuraLube fuel cleaner.

All are good, and all will make significant inroads on carbon buildup on valves.

Marvel is still 50 year old technology with some minor inprovements and probably won't help much.

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I totally agree, the exhaust valves are very likely to burn the valve and seat leading to needing the head pulled and valve job(just finished one yesterday). The exhaust valve in this case had a huge chunk burnt away and the seat was elongated. I have seen this many times on the regular coopers, more likely with light footed drivers with the statistics I have seen. In my region, seems to be more attributed with fuel also, as there is no correlation with Prod. date. Ran through a string of them a year or so and now just come in every so often(1 every 2 months)

I ported and polished a head for my car(Justacooper)02 MC and the gains were IIRC about 8hp and 10 ftlbs of torque...

 

I'm assuming that by light footed drivers you mean the opposite of lead foot.. would shifting at 3K be considered light footed ?

 

To me it would...considering I shift at no less than 5k all the time....

 

 

I put a pint of Seafoam in the crankcase & a pint in the gas, ran to Portland & back on Sunday.. so when that tank is done I'll see if it made a difference in my compression..
Thanks.