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MG MGF Technical - Tappets tapping?

Hi all, I'd like to rack your brains if I may.

My 1998 F developed a ticking noise several months back, after checking the archives on this BBS I pretty sure that the tappets are clogged. However, the F had it's annual service at the beginning of this month, which obviously involved an oil change. Having done this I noticed that tapping had gone completely. Great methinks, nice cheap solution. Predictably about 2 weeks later the tapping returns, although it's slightly more erractic. By this I mean that sometimes the tapping it very obvious but other times it's completely absent.

Surely if the tappets were clogged they would be ticking away all of the time, but when the oil temp reaches around 90/95 deg. it goes quiet and the engine runs normally. Anything cooler than this and the ticking comes back.

Bit of a mystery, but the F's going back in next week for brakes so I'll get the chaps to have a look then. Does anyone have any idea what it could be?

Thanks in advance,

Em Jackman
Emma Jackman

Hi Emma,
ask the garage what spec. for the oil they used for service. 10W-40 oil makes tappet noise on / off in my F ,and just as in your case dissapears after a long drive with oiltemp well above 100 deg.C A thinner oil might be better ( I have tried 0W-40 ) but even if it takes away some of the ticking noise fom the tappets I think it might be too thin as the car is being used for spirited driving on track-days as well.
In UK there is the Castrol Magnatec that is said to be good for eleminating tappet noise.
It seems that the tappet noise is a "feature", something we have to live with.. And also,in an "ordinary" car there is a lot of isolation on top of the bonnet over the camcover. In the "F" there is no such sound dampening , one can see the camcover tru the vents and of course this amplifies any "normal" sounds.
It would be interesting to hear from the engine gurus their understanding of the tappet noise from the K-engine. Air in the oil,sloppy sealing in the tappets or just plain normal? / Carl.
Carl

Cheers Carl,

Forgot to mention, they used Castrol, 10/40 semi synthetic oil which I believe is recommended for the F.

Emma
EmGeeEff.tk
Emma Jackman

Em

Th w has no effect on high temp performance. The base oil effects high temp performance, ester synthetic better than PAO synthetic better than semi.

A semi is basically mineral oil with say 20% synthetic, so cost effective but not high performance.

The problem with a mineral base is that the viscosity will reduce by say 30% within a short time (2000miles)and produce varnish and sludge (clogging matter).

If you consider clogging matter is an issue the engine can be cleaned up using Redline (although expensive) or a quality synthetic (M1, Silkolene, Motul).

If M1 0W40 is not suitable then the viscosity can be changed by adding some M1 15W50, this is not an issue as PAO synthetics are blended in this way.

Tapping noises are common on many cars including supercars and changing oils even from factory recommended can be a cure.

Paul
Paul

Had the same problem with mine. Posted it on here and one guy suggested a good run was needed as i use the car only at weekends. The ticking on mine always went when it was warm.I gave the car a really good run ,for over a hour,and the ticking noise went.It is now only there when the car is not used for long periods, a gentle warm up and then a good hard drive seems to be all mine needs.IT has always been well serviced and has 68,000 on the clock,im sure you have nothing to worry about as this seems quite common .........mel.......
m e johnson

Thanks to Paul and Mel,

As long as I'm not doing any damage to my engine by letting the tapping continue, the tapping itself doesn't bother me. There's definately no pattern to it, sometimes the engine's cold, warm and hot, the tapping can occur at any point. I think by the sounds of it, it's just a character fault.

Emma
http://EmGeeEff.tk
Emma Jackman

Em,

Unless you have oil starvation or rust corrosion sticking parts, "noises" are not normally a wear issue unless a sudden change to the noise occurs.

There are anti wear additives in oil such as esters (Magnatec advert) these actually coat metal surfaces with a layer of oil and do not drain back, and zinc and moly which protect metal surfaces under pressure also Boron found in M1, so oils are good at protecting from wear.

Paul
Paul

Not always the case Paul with Hydraulic tappets - oil sludge can block the oil paths into the tappet, causing it to incompletely fill - effectively causing it to stick.

A good oil flush can work wonders.

If the noise is only at start up & disappears quickly, the oil is at the correct level and is in good condition, and it doesn't annoy you too much, then ignore it. The tappets will still have many 1000s of miles of life in them. Replacement of tappets is for the deep of pocket - you usually have to replace all 16!!!
Rob Bell

Thanks Rob, sometimes the ticking happens when I start up and disappears after the oil hits 90 deg. On the other hand sometimes it starts up cold and doesn't tick, but then starts ticking when the engine has warmed up. Weird!

Emma
http://EmGeeEff.tk
Emma Jackman

Hi,Emma,

Warning......lengthy post!

The reason that the "tappets" or actually known as Hydrualic Valve Lifters (or Hydraulic Lash Adjusters or Cam Followers), make noise at startup and sometimes not, is because of where the cam lobes stop when you turn off the engine.
If a "suspect" HVL is left under pressure (in other words if the cam lobe is pushing down on the top of the valve), then it will certainly drain oil out and so next time on startup it will take time to pump it up. If infact hat particular HVL is "clogged" then it will tkae extra time to get oil in it to do it's job.
If it stops with no pressure on it, then the oil may stay in there longer and chances are it will not make noise when you startup next time.
If you buy yourself a cheap mechanics stethoscope for a few pounds, you will be able to hear which area the noise is coming from.
This tool is great for tracking down those annoying noises that we all hate to hear.

The design of a HVL is to keep a "no gap" situation between the cam lobe and the top of the valve. Noise = Gap. What this means is that in time, the surfaces between the lobe and the valve caps will become scored and brittle due to impact.

I would investigate further to try and "stop" the noise. Your call though.

Oh, here's a former thread with some info (and links) that may be of use.

http://www2.mgcars.org.uk/cgi-bin/gen5?runprog=mgbbs&mode=archiveth&subject=69&subjectar=69&thread=200503030229333418


Cheers,
Branko.
Branko

A continual ticking on mine drove me crazy for ages. Eventually I tracked it down to a loose oil filler and dipstick. It was loose and rattled when the engine was revved.
Bob Millar

Rob,

The sludge issue is same as oil starvation. With regard to sludge build up I would recommend a quality synthetic especially ester based. Flushing should not be needed as I see no point in letting sludge build up and then trying to clean up mess, much better to spend money on quality oil, if you intend long term ownership. I would also change a non synthetic at least every 6k miles although OCI depends on use.

Branko

Interesting comments and the "stopping" position certainly applies to the rust/corrosion issue.

Ticking on start up perhaps can be expected because of drainback and until the oil reaches
HVLs they will be "dry" (esters and aw additives will still be on surface) and a thin oil film. Viscosity effects drainback and a thick oil will leave a thicker oil film and lessen any noise, in addition a non synthetic contains a greater % of additives which also may effect the noise level .
The ticking noise should cease once oil flow has been established which should be within first few seconds at start up. At start up the oil flow may change slightly if using a thin start up oil say 0W compared to 10W and with ambients and "tick time" may vary. Another variable would be the metal parts expanding as the engine warms up. With a sludge issue the ticking may not cease until the oils has thinned, as an oil tends to follow path o least resistance.


Tick at operating temps (I will need to reread your link) but if you have ticking with a 0W30 oil at 100c (I would not use this type of oil if low HTHS) then you would also get ticking at say 120c with a 0W40.

The volume of oil flow does not change whether 0W30 or 0W40 although there will be a subtle change in oil flow between grades and oil temperatures.

Paul
Paul

Just got back from the garage. The F decided to make me look like a lier, and didn't tick this morning. I was told that with the hydrolic tappets, if you only do short journeys (I usually do 3 miles each way to work every day) the air can get trapped in the tappets which can cause the ticking. If you go out on a longer run the should let the air escape, and hence the ticking stops. Well, at least that didn't cost me anything!

Emma
http://EmGeeEff.tk
Emma Jackman

This thread was discussed between 23/07/2005 and 28/07/2005

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