KV6 Missfire and Mayo

thanos.m · 9th December 2020, 10:29

Hi all,
I Went to start my 75 this morning and it wasn't particularly happy about it struggled but it fired up with a very noticeable missfire (plugs were done in August) although it seemed to clear up after a minute or so. In general it hasn't been very happy starting cold lately. Besides sometimes when cold moving from R to P or from to N it almost wants to die but I havent thought much of it as whether has been getting cold. I scanned the car and it came up with cylinder 3 missfire I also opened the oil cap and it was full of mayo I had issues in the past but it hadn't make its appearance in while now of course I panicked and thought my head gasket is gone so block leak tested the car and it came out fine. The car has been running cold and a thermostat is on the way so this may explain the mayo but there was a lot of it. I'm a bit baffled as to what's going any ideas ?

SD1too · 9th December 2020, 11:25

Hi Thanos,

The mayonnaise is very likely to be the result of the engine running cold. If not, the oil cooler could have failed.

The misfire may be an ignition coil failing. I had this on no. 5 last year. Eventually the engine wouldn't start at all.

Simon

thanos.m · 9th December 2020, 12:05

Quote:

Originally Posted by SD1too

Hi Thanos,

The mayonnaise is very likely to be the result of the engine running cold. If not, the oil cooler could have failed.

The misfire may be an ignition coil failing. I had this on no. 5 last year. Eventually the engine wouldn't start at all.

Simon

Great thanks Simon,
I wondering if it could be Inlet manifold gaskets I know they can be an issue on the K-series with some of the effects I'm describing but I'm not sure if they fail on the kv6 ?

trikey · 9th December 2020, 12:26

Quote:

Originally Posted by thanos.m

Great thanks Simon,
I wondering if it could be Inlet manifold gaskets I know they can be an issue on the K-series with some of the effects I'm describing but I'm not sure if they fail on the kv6 ?

That’s what I was going to suggest!

vitesse · 9th December 2020, 13:48

Quote:

Originally Posted by thanos.m

Great thanks Simon,
I wondering if it could be Inlet manifold gaskets I know they can be an issue on the K-series with some of the effects I'm describing but I'm not sure if they fail on the kv6 ?

They do indeed fail, have a look at this recent thread: https://www.the75andztclub.co.uk/for...d.php?t=309291

Regards

COLVERT · 9th December 2020, 13:55

Cold, damp morning.

Spray the ignition leads with WD 40.----Stop that tracking.

9th December 2020, 10:29	#1
thanos.m Avid contributor Rover 75 saloon Join Date: May 2019 Location: West Sussex Posts: 224 Thanks: 54 Thanked 41 Times in 26 Posts	KV6 Missfire and Mayo Hi all, I Went to start my 75 this morning and it wasn't particularly happy about it struggled but it fired up with a very noticeable missfire (plugs were done in August) although it seemed to clear up after a minute or so. In general it hasn't been very happy starting cold lately. Besides sometimes when cold moving from R to P or from to N it almost wants to die but I havent thought much of it as whether has been getting cold. I scanned the car and it came up with cylinder 3 missfire I also opened the oil cap and it was full of mayo I had issues in the past but it hadn't make its appearance in while now of course I panicked and thought my head gasket is gone so block leak tested the car and it came out fine. The car has been running cold and a thermostat is on the way so this may explain the mayo but there was a lot of it. I'm a bit baffled as to what's going any ideas ?

9th December 2020, 11:25	#2
SD1too Doesn't do things by halves Rover 75 2.5 Connoisseur Auto (1999) Dealer launch model. Join Date: Mar 2007 Location: Former Middlesex Posts: 20,382 Thanks: 1,587 Thanked 3,749 Times in 3,181 Posts	Hi Thanos, The mayonnaise is very likely to be the result of the engine running cold. If not, the oil cooler could have failed. The misfire may be an ignition coil failing. I had this on no. 5 last year. Eventually the engine wouldn't start at all. Simon __________________ "Whatever is rightly done, however humble, is noble." Sir Henry Royce.

9th December 2020, 13:55	#6
COLVERT This is my second home R75 Saloon. Join Date: Feb 2009 Location: France/or Devon. Posts: 14,003 Thanks: 3,851 Thanked 2,167 Times in 1,816 Posts	Cold, damp morning. Spray the ignition leads with WD 40.----Stop that tracking.