Mi Has Exploded!

[pacey205 2]

My Mi has taken a turn for the worse. Driving back home suffered a loss in power and started running a bit lumpy. Was on a dual carriageway with nowhere to pull over at the time so didn't stop immediately. Car still drove okay but with much reduced power and the rough running, not quite running on 3 cylinders style but obviously not 100%. No warning lights on, oil pressure was okay, no plumes of smoke anywhere etc.

 

So I limped the car home and opened the bonnet to find oil everywhere and what appeared to be smoke coming out of the dipstick. Removed the oil filler cap and it seems that the sump is pressurised (can feel it pulsing out of the oil filler/dipstick).

 

My first thought was rings have gone somewhere, hence lack of power but am also thinking it could maybe be the head gasket also.

 

So first plan of attack is to do a compression test and go from there but has anyone else got any ideas on possible causes etc.

 

Biggest ballache is that the missus is in Leicester so Im home alone. Cycling to work tomorrow it is then!

 

Michael

[dcc 855]

Could be the rings, by the sounds of it any way. I would rule out a hole in the piston with there being no smoke out the back. Compression test wont rule out if its the head or rings. drop some oil down the bores, just a little, if you get better compression then its the rings, if not then it could be the gasket.

[pug_ham 244 3 Cars]

Pressure out of the oil filler tube is normal with an engine running, all engines will have this.

 

How else is the volume of air in the sump going to escape?

 

Smoke out of the dipstick could just mean its oil change time but if its excessive can be a sign of worn rings.

 

You haven't got a leaky rocker cover seal have you so the plug holes have filled with oil causing it to misfire & spray poil around the engine bay or something simple like that?

 

Graham.

[sub205 5]

overpressure on the crankcase can also mean your air system is closed somewhere. many cars had this problem this winter because the oil/water-mixture in the hoses froze and the engine built up pressure in the crankcase, pushing oil out of the dipstick.

 

doing a compression-test usually is not a bad idea, if its really a worn piston(ring) you can easily swap with another liner/piston-combination and new bearings, so no problem at all in my oppinion. the 1.9litre engines are much easier to maintain in such cases as the 2.0...

[pacey205 2]

Right slight update.

 

Compression test showed that two of the cylinders had very low compression, i.e. 5psi (No 1 (counting from cambelt end) and No 3) whereas the other two were 180psi. So decided to take the head off and see what was what.

 

Drained oil and coolant to see no evidence of oil and water mixing, both were very clean. Took the head off and the gasket dosent look too bad. Fire rings all look to be in reasonable nick (no sins of any breaks etc), oil chambers are similar with no obvious breaks.

 

 

However around the water holes the gasket looks to be in pretty bad condition, it has bubbled and split almost all the way around but I cant see any sections were it has crossed into an oil hole, fire ring. Is this normal, I expected this to be in better condition than it is (considering it has done 20,000 miles since a complete rebuild).

 

 

Continued on next post

Edited April 18, 2010 by pacey205

[pacey205 2]

Looking at the liners the to pistons with good compression you can still see the honing marks (from the rebuild) but the cylinders with low compression seem to have much heavier wear (one in particular). The one with the heaviest wear (cant see honing marks, only vertical wear marks) also corresponds to oily looking valves, although the other low compression cylinder valves are of a similar condition.

 

No 1 (Cambelt End, low compression, cant see honing marks, relatively heavy vertical wear marks, slightly oily looking valves)

 

No 2 (can still see honing marks, valves/head looks in good nick)

 

No 3 (heavy wear marks, no honing marks visible, very oily valves/head)

 

No 4 (can still see honing marks, valves/head look in good nick)

My thoughts are that rings look the most likely candidate which is incredibly annoying seeing as they were new 20k ago. Anyone else have any views/suggestions/easy fixes?

 

Michael

Edited April 18, 2010 by pacey205

[davev 1]

first thing to do is get a rag down the bores and wipe off the oil from inside liners, as most of the marks look like oil. if you then still have heavy wear marks going vertically down then theres a problem with the rings imo. and itll mean new rings again and liners checked and rehoned/replaced.

[pacey205 2]

Well worst looking piston out and there is very heavy wear, both the liner and the piston. The rings are actually locked solid in the their slots.

 

 

On the liner whilst there is wear around the entire liner, there is much heavier wear at the four valve positions. There is also damage at two of the valve cutouts on the piston (one inlet and one exhaust, daigonally opposite). There is no sign of any detonation on the piston itself.

 

 

The thing I cant quite get my head around is the amount of wear to the piston/liner. The oil pressure/temp was good (no warning lights etc). I was wondering along the lines of something fuelling related causing the piston to run really lean maybe, inoperative injector or something, does this sound like a possibility.

 

Have any of the engine gurus got any ideas?

 

Michael

[sport1901966 8]

Could it be the opposite, i.e. cylinders running very rich causing borewash. Although the injection system is batch fire so all injectors should be injecting the same quantity of fuel. It would be interesting to see the results of an injector test comparing all four.

 

Have you checked to see if the cylinder oil spray bars are blocked on those cylinders?

Edited April 24, 2010 by sport1901966

[pip470 61]

 

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This picture looks like it has been eaten away by detonation, Its obviously got really hot and picked up causing the rapid bore wear. Your lucky the engine didnt seize in my opinion. So I would check the injectors, and the piston squirter's .

[craig_007 1]

Hi Mate,

 

Sorry I can't add to this but I will follow the thread.

 

The very same thing happened to my engine,Rings siezed to piston and serious wear on piston/liner(Piston 4 at timing belt end) Caused heavy breathing (Oil all over engine bay),I got away with changing 1 piston and hoaning liner.

 

The conrod for that piston also had wear on the small end,I checked the other 3 pistons and rods and there was not a mark on them.

 

I also never got to the bottom of what caused it. I checked for oil problems I.E Piston squirters, They were fine.

 

When this did happen the engine still sounded fine, When I stripped the engine the crank/bearings were all unmarked.

 

I put it down to oil temp as that was the only gauge I didn't have working at the time,I will be interested to see if you come across something else.

 

Good Luck

[pacey205 2]

Thats very interesting craig. Looking at mine its a similar situation as the bearings are okay, although the small end seems to be fine also. Quickly checked the piston squirters and they dont appear to be blocked.

 

I was wondering if it was an issue with the injectors (i.e. injector failure), or possibly something management related. Any ideas on an easy way to test the management (test injector plugs maybe) and the injectors?. Ill have a quick search now.

 

What does anyone think to it being a managment issue. Im a little worried as Im putting another Mi in to get the car back on the road and Im slightly aprehensive that if it is a management issue a similar thing could well occur on the new engine :S

 

Michael

Edited April 29, 2010 by pacey205

[Jrod 7]

http://forum.205gtidrivers.com/index.php?s...10394&st=50

 

Same thing happened to mine, just doesnt look as bad. Number 4 piston aswell.

 

The injectors had only been tested a few months before so don't think its them on mine.