Engine noise on startup

barry · 9th December 2020, 04:07

Good morning
Any ideas on what may be the origin of a light to medium metallic noise (knock?) from the engine of my ZT180 (2.5 V6) on startup.
If engine is left on idle at start (1000rpm), noise remains for about 20 secs. If rpm is increased to 1600-1800, the noise will disappear in 4-5 secs. Seems oil pressure/feed related.
Wondering what component could be the cause. Seems a bit too audible initially to be a tappet.
Cambelt(s), water pump, thermo', tensioners etc. replaced around 12 months back and noise has appeared since then. Motor has done 83000kms and very seldom over 4000rpm. Thanks for any ideas.
Stay safe folks
Barry

trikey · 9th December 2020, 06:28

Could be a tappet, try an engine flush and fresh oil to see if that cures things.

Teflon · 9th December 2020, 08:06

The symptoms you describe are the similar to what I had with my 2.0 V6. Only ever occurred when the engine was stone cold and would run fine once the noise stopped.

Lot's of suggested causes, including belt related; sticking tappet; oil pressure problems; oil pick up tube; however in my case, it was eventually correctly diagnosed as piston slap. Engine mileage was 75K and like yours, seldom revved above 4K. See here (The noise starts around 19 seconds into the video):

I was advised that it was relatively harmless at this stage, but I had it fixed anyway.

Cliff

SD1too · 9th December 2020, 09:41

Quote:

Originally Posted by barry

Any ideas on what may be the origin of a light to medium metallic noise (knock?) from the engine of my ZT180 (2.5 V6) on startup.
If engine is left on idle at start (1000rpm), noise remains for about 20 secs. If rpm is increased to 1600-1800, the noise will disappear in 4-5 secs.

Hello Barry,
I had those symptoms some years ago and found a cut across the rubber of the ancillary belt. Later I renewed the tensioner and that made the biggest difference. Were these looked at when your cambelts were renewed?

Tappet noise can usually be confirmed by placing your ear just above the cam covers!

Simon

Teflon · 9th December 2020, 11:01

Probably worth mentioning that when mine was finally diagnosed correctly, the mechanic (Russell Walsh from MG Rover Solutions) did so by removing the engine cover and using a long screw driver as a stethoscope. When placed against the front engine bank he was able to clearly identify the source of the noise.

Has to be worth a try as it costs nothing and takes 5 minutes max

Cliff

MacRob · 9th December 2020, 12:40

Quote:

Originally Posted by Teflon

The symptoms you describe are the similar to what I had with my 2.0 V6. Only ever occurred when the engine was stone cold and would run fine once the noise stopped.

Cliff

Had the same problem on my 2ltr v6 45. It did that for the 3 years and 18k miles I owned it. Didn’t affect the running of the car and again was only doing so at start up and not every time.
The fact that the car only cost me £100 as it only had 3 days MOT left on it, I never bothered to much about it. I did add an oil treatment to it designed to free up sticking valves and rings, which did help a lot.

COLVERT · 9th December 2020, 13:47

Post 3 above. Will very quickly add or remove the tappet theory from your search.

barry · 10th December 2020, 03:47

Thanks to Cliff, Simon, Colvert and MacRob
Tensioner was renewed along with the belts. Have got a stethoscope so will have another go at sorting the origin of the noise. Wasn't very conclusive at last attempt using it. Am leaning toward either a tappet or a piston. Noise is inaudible once temp and oil flow rise, so will not be dismantling anything at this stage just the engine cover. Had a Montego from new which had a vaguely similar noise at idle all its life. It covered 200K kms plus, with no change and without any definite resolution.
Will post if anything significant shows itself.
Many thanks
Barry

9th December 2020, 04:07	#1
barry Regular poster mg zt 180 sport Join Date: Oct 2007 Location: auckland Posts: 50 Thanks: 0 Thanked 5 Times in 5 Posts	Engine noise on startup Good morning Any ideas on what may be the origin of a light to medium metallic noise (knock?) from the engine of my ZT180 (2.5 V6) on startup. If engine is left on idle at start (1000rpm), noise remains for about 20 secs. If rpm is increased to 1600-1800, the noise will disappear in 4-5 secs. Seems oil pressure/feed related. Wondering what component could be the cause. Seems a bit too audible initially to be a tappet. Cambelt(s), water pump, thermo', tensioners etc. replaced around 12 months back and noise has appeared since then. Motor has done 83000kms and very seldom over 4000rpm. Thanks for any ideas. Stay safe folks Barry

9th December 2020, 06:28	#2
trikey Premium Trader Rover 75 Join Date: Nov 2010 Location: Devon Posts: 33,764 Thanks: 8,837 Thanked 14,831 Times in 8,030 Posts	Could be a tappet, try an engine flush and fresh oil to see if that cures things. __________________ Lest we forget..

9th December 2020, 08:06	#3
Teflon This is my second home Lagoon 2.0 V6 75 Conn SE Saloon Join Date: Nov 2006 Location: Chertsey Posts: 5,201 Thanks: 2,825 Thanked 2,920 Times in 1,570 Posts	The symptoms you describe are the similar to what I had with my 2.0 V6. Only ever occurred when the engine was stone cold and would run fine once the noise stopped. Lot's of suggested causes, including belt related; sticking tappet; oil pressure problems; oil pick up tube; however in my case, it was eventually correctly diagnosed as piston slap. Engine mileage was 75K and like yours, seldom revved above 4K. See here (The noise starts around 19 seconds into the video): I was advised that it was relatively harmless at this stage, but I had it fixed anyway. Cliff __________________ No. 4 of 6 Last edited by Teflon; 9th December 2020 at 08:46..

9th December 2020, 11:01	#5
Teflon This is my second home Lagoon 2.0 V6 75 Conn SE Saloon Join Date: Nov 2006 Location: Chertsey Posts: 5,201 Thanks: 2,825 Thanked 2,920 Times in 1,570 Posts	Probably worth mentioning that when mine was finally diagnosed correctly, the mechanic (Russell Walsh from MG Rover Solutions) did so by removing the engine cover and using a long screw driver as a stethoscope. When placed against the front engine bank he was able to clearly identify the source of the noise. Has to be worth a try as it costs nothing and takes 5 minutes max Cliff __________________ No. 4 of 6

9th December 2020, 13:47	#7
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	Post 3 above. Will very quickly add or remove the tappet theory from your search.

10th December 2020, 03:47	#8
barry Regular poster mg zt 180 sport Join Date: Oct 2007 Location: auckland Posts: 50 Thanks: 0 Thanked 5 Times in 5 Posts	Thanks to Cliff, Simon, Colvert and MacRob Tensioner was renewed along with the belts. Have got a stethoscope so will have another go at sorting the origin of the noise. Wasn't very conclusive at last attempt using it. Am leaning toward either a tappet or a piston. Noise is inaudible once temp and oil flow rise, so will not be dismantling anything at this stage just the engine cover. Had a Montego from new which had a vaguely similar noise at idle all its life. It covered 200K kms plus, with no change and without any definite resolution. Will post if anything significant shows itself. Many thanks Barry