1.8t low compression on cylinder 1 -Head off results

Yorkshire GOC · 29th January 2021, 13:17

At the end of December i had a slight hardly noticeable misfire - generating Code 0300 multiple misfire - the misfire got more frequent and stronger. Garage did a compression test and got
Cyl 1 60psi
Cyi 2,3 and 4 all 120 psi.

So took car to engine repair specialist who clearly seems to know K series engine. Head off - Head gasket fine - in fact he could find no faults - but whilst there reconditioned the cylinder head, cleaned the pistons, fitted new Piton rings, new big end bearings and new gasket. He said the engine was looking good and the liners came out a treat - always a good sign he said. He also test drove her and all was OK.

So i got in the car and as i was backing out of the yard -the EML flashed, she stalled and juddered - he put his code reader on her (a pro code reader set for MG 1.8T) and we got 0300 multiple misfire and a new one 0171 fuel trim out of range as well as my long time friend 0443 (Purge valve circuit) . So we ran a compression test engine was cold i throttled her and he did the measuring and we got
Cylinder 1 170 psi
Cylinder 2 170 psi
Cylinder 3 150 psi
Cylinder 4 130 psi

He was gobsmacked so its head off again as he wants to get to the root of the problem

Am wondering if i have an electrical or vacuum issue in view of 0171 - the purge vale code i have had for 6 years - replaced valve/circuits checked - but i wonder if it is stuck open letting in unmetered air?

T-Cut · 29th January 2021, 13:39

Quote:

Originally Posted by Yorkshire GOC

Am wondering if i have an electrical or vacuum issue in view of 0171 - the purge valve code i have had for 6 years - replaced valve/circuits checked - but i wonder if it is stuck open letting in unmetered air?

I suspect it's unlikely, but you could try blanking off the purge valve to manifold pipe, which would eliminate the possibility.

TC

WillyHeckaslike · 29th January 2021, 18:38

Maybe check that the height of the dowels are within spec and that extra care is given to the initial 20nm torque load on the head bolts. Personally, I would also fit the stronger oil rail on our 1.8s as the weaker OEM version was found to be too weak and prone to cracking. Not good as it is the anchor for the sandwich construction of the engine. Ignore any claims that the cracking was only on the Freelander variant, I've seen the problem flagged up on other forums re a number of Rover variants including the 25/ZR.

COLVERT · 29th January 2021, 19:08

Quote by the OP.---At the end of December i had a slight hardly noticeable misfire - generating Code 0300 multiple misfire - the misfire got more frequent and stronger. Garage did a compression test and got
Cyl 1 60psi
Cyi 2,3 and 4 all 120 psi.

CYL 1.---Normally that sort of reading has perhaps three causes.

1/ piston rings.
2/ valves.
3/ head gasket.

Can't think what it would be if not one of those.--

trikey · 29th January 2021, 19:20

Did the mechanic take a few mm of the head bolts Martin?

rrobson · 29th January 2021, 19:21

What exactly was done to the head? I hope they lapped the valves while they were reconditioning it...
What were the new ring gaps? New doesn’t always mean correct.
We’re the liner heights correct?
What gasket was fitted? There are some spurious low quality items out there.

Also interested to hear why the bearings were changed, were they pitted or scored? Were they measured on strip down and new measured on refit?

Vacuum or purge systems won’t affect the compression test, but that isn’t to say either could me causing a misfire.
Head cracking is uncommon but not an impossibility, however you wouldn’t have compression issues moving from one side to the other.
As said above, there are only three things that can affect compression so something is amiss there.

— trikey, that’s an issue I haven’t seen for a while, head bolts bottoming out on the sump! Would cause issues on the gearbox side

bsafly · 29th January 2021, 20:20

Definitely time for a cylinder leak down test if the engine has not been stripped down yet - it will at least point you in the right direction so you know roughly where to look when you get inside the engine, it's an invaluable diagnostic tool if used correctly.

Yorkshire GOC · 8th February 2021, 14:21

Well the head was taken off again - and the low compression was caused by 2 of the rings not bedding properly. All along the guy said your symptoms sound like coil packs to me (obvious answer ) - beside the low compression and that is now sorted - but he also swopped out the coil packs with what he called "proper" MGR coil packs he sourced from a local scrappy.

He also said the Engine was to quote in "superb" condition.

So picked car up on Tuesday and the engine sound was markedly beefier and she drove sweet all the way home . Anyway last Friday did 40 miles at motorway speed and all was fine with no misfires. So hopefully all sorted.

My confidence in his knowledge of the K series was re-enforced as they refilled the coolant (Bluecol as well) spot on - and she is now running absolutely as i would expect temp wise with no air locks . He also remarked on my MG 7 engine cover - he said in all his years on MGR 1.8's he had never seen that engine cover before.

bsafly · 8th February 2021, 15:01

Excellent, glad you got it sorted.

trikey · 8th February 2021, 15:34

About blooming time 😀

Worth plugging the garage I reckon Martin..

Sent from my iPhone using Tapatalk

29th January 2021, 13:17	#1
Yorkshire GOC I really should get out more....... Rover 75 connoisseur se v6 auto Join Date: May 2014 Location: Hull Posts: 2,063 Thanks: 1,842 Thanked 623 Times in 469 Posts	1.8t low compression on cylinder 1 -Head off results At the end of December i had a slight hardly noticeable misfire - generating Code 0300 multiple misfire - the misfire got more frequent and stronger. Garage did a compression test and got Cyl 1 60psi Cyi 2,3 and 4 all 120 psi. So took car to engine repair specialist who clearly seems to know K series engine. Head off - Head gasket fine - in fact he could find no faults - but whilst there reconditioned the cylinder head, cleaned the pistons, fitted new Piton rings, new big end bearings and new gasket. He said the engine was looking good and the liners came out a treat - always a good sign he said. He also test drove her and all was OK. So i got in the car and as i was backing out of the yard -the EML flashed, she stalled and juddered - he put his code reader on her (a pro code reader set for MG 1.8T) and we got 0300 multiple misfire and a new one 0171 fuel trim out of range as well as my long time friend 0443 (Purge valve circuit) . So we ran a compression test engine was cold i throttled her and he did the measuring and we got Cylinder 1 170 psi Cylinder 2 170 psi Cylinder 3 150 psi Cylinder 4 130 psi He was gobsmacked so its head off again as he wants to get to the root of the problem Am wondering if i have an electrical or vacuum issue in view of 0171 - the purge vale code i have had for 6 years - replaced valve/circuits checked - but i wonder if it is stuck open letting in unmetered air? __________________ She came off the Longbridge Line on 20-05-2003 The Silver Machine was the 13th of 160 Rover 75's to come off the production line that day and is the 100th of 527 Starlight Silver Rover 75 2.5 V6 Connoisseur SE Auto saloons listed in the build records produced world wide.

29th January 2021, 19:20	#5
trikey Premium Trader Rover 75 Join Date: Nov 2010 Location: Devon Posts: 33,763 Thanks: 8,837 Thanked 14,831 Times in 8,030 Posts	Did the mechanic take a few mm of the head bolts Martin? __________________ Lest we forget..

29th January 2021, 19:21	#6
rrobson I really should get out more....... 75 tourer cdti, MG ZS 180, nissan terrano & 1.8t rover 25 Join Date: Feb 2010 Location: Pontefract Posts: 2,643 Thanks: 17 Thanked 295 Times in 218 Posts	What exactly was done to the head? I hope they lapped the valves while they were reconditioning it... What were the new ring gaps? New doesn’t always mean correct. We’re the liner heights correct? What gasket was fitted? There are some spurious low quality items out there. Also interested to hear why the bearings were changed, were they pitted or scored? Were they measured on strip down and new measured on refit? Vacuum or purge systems won’t affect the compression test, but that isn’t to say either could me causing a misfire. Head cracking is uncommon but not an impossibility, however you wouldn’t have compression issues moving from one side to the other. As said above, there are only three things that can affect compression so something is amiss there. — trikey, that’s an issue I haven’t seen for a while, head bolts bottoming out on the sump! Would cause issues on the gearbox side __________________ How to view a car - everything you need to help you inspect a used car VIS motor tester avalible to local members Injector removal tool and auto gearbox pressure tester now available Last edited by rrobson; 29th January 2021 at 19:24..

29th January 2021, 20:20	#7
bsafly Just going about! Rover 75 CDTi Connie SE Tourer starlight silver and serpents. MG ZT-T 190+ in Raven Black. Join Date: Mar 2016 Location: Great Leighs Posts: 468 Thanks: 626 Thanked 167 Times in 110 Posts	Definitely time for a cylinder leak down test if the engine has not been stripped down yet - it will at least point you in the right direction so you know roughly where to look when you get inside the engine, it's an invaluable diagnostic tool if used correctly. Last edited by bsafly; 30th January 2021 at 10:57.. Reason: Correction

8th February 2021, 14:21	#8
Yorkshire GOC I really should get out more....... Rover 75 connoisseur se v6 auto Join Date: May 2014 Location: Hull Posts: 2,063 Thanks: 1,842 Thanked 623 Times in 469 Posts	Well the head was taken off again - and the low compression was caused by 2 of the rings not bedding properly. All along the guy said your symptoms sound like coil packs to me (obvious answer ) - beside the low compression and that is now sorted - but he also swopped out the coil packs with what he called "proper" MGR coil packs he sourced from a local scrappy. He also said the Engine was to quote in "superb" condition. So picked car up on Tuesday and the engine sound was markedly beefier and she drove sweet all the way home . Anyway last Friday did 40 miles at motorway speed and all was fine with no misfires. So hopefully all sorted. My confidence in his knowledge of the K series was re-enforced as they refilled the coolant (Bluecol as well) spot on - and she is now running absolutely as i would expect temp wise with no air locks . He also remarked on my MG 7 engine cover - he said in all his years on MGR 1.8's he had never seen that engine cover before. __________________ She came off the Longbridge Line on 20-05-2003 The Silver Machine was the 13th of 160 Rover 75's to come off the production line that day and is the 100th of 527 Starlight Silver Rover 75 2.5 V6 Connoisseur SE Auto saloons listed in the build records produced world wide. Last edited by Yorkshire GOC; 8th February 2021 at 14:25..

29th January 2021, 18:38	#3
WillyHeckaslike This is my second home Rovers 75 & 25 Join Date: Oct 2010 Location: Wearside Posts: 4,519 Thanks: 543 Thanked 709 Times in 511 Posts	Maybe check that the height of the dowels are within spec and that extra care is given to the initial 20nm torque load on the head bolts. Personally, I would also fit the stronger oil rail on our 1.8s as the weaker OEM version was found to be too weak and prone to cracking. Not good as it is the anchor for the sandwich construction of the engine. Ignore any claims that the cracking was only on the Freelander variant, I've seen the problem flagged up on other forums re a number of Rover variants including the 25/ZR.

29th January 2021, 19:08	#4
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	Quote by the OP.---At the end of December i had a slight hardly noticeable misfire - generating Code 0300 multiple misfire - the misfire got more frequent and stronger. Garage did a compression test and got Cyl 1 60psi Cyi 2,3 and 4 all 120 psi. CYL 1.---Normally that sort of reading has perhaps three causes. 1/ piston rings. 2/ valves. 3/ head gasket. Can't think what it would be if not one of those.--

8th February 2021, 15:01	#9
bsafly Just going about! Rover 75 CDTi Connie SE Tourer starlight silver and serpents. MG ZT-T 190+ in Raven Black. Join Date: Mar 2016 Location: Great Leighs Posts: 468 Thanks: 626 Thanked 167 Times in 110 Posts	Excellent, glad you got it sorted.

8th February 2021, 15:34	#10
trikey Premium Trader Rover 75 Join Date: Nov 2010 Location: Devon Posts: 33,763 Thanks: 8,837 Thanked 14,831 Times in 8,030 Posts	About blooming time 😀 Worth plugging the garage I reckon Martin.. Sent from my iPhone using Tapatalk __________________ Lest we forget..

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