2500TC Engine making odd noises.

[Wagger]

Having spent many hours in the engine bay of my 2500 Vitesse recently I noticed odd noises. Some random and others cyclic. The random one is at precisely 2300 rpm on the tacho and sounds like a sharp 'Ting' common to a chain hitting casing or tensioner. Many years ago a cam on an OHC engine I owned had a step in it and made this noise (like playing 'Tiddley Winks' on a Xylophone) but that was every turn of the cam. If I decrease engine speed this becomes 'Cyclic' like a big or small end. If I increase revs above 3000 it disappears altogether. Maybe I'll get the wooden stethoscope out tomorrow.

I know that the Tappets (Cam followers) rotate as do the pushrods and they cause 'Cyclic' noises that come and go it time with firing strokes. I did find a loose piece of harness tape randomly hitting the fan and thought that was it. Sadly, I was wrong.

The engine burns no oil. The oil is clean and the exhaust belches nothing too nasty. I suspect I may have a sticking valves, so removing the rocker cover and watching each one may reveal something. The car did stand dry stored for five years, so it quite unbelievable that it runs at all. Could be random 'Pinking' on one cylinder too if the distributor is a bit eccentric.

The sump is coming off soon to do the thrusts as there is about 12 thou of endfloat and I will check all of the shells whilst I am at it. Will bash the sump in too. Timing cover off is easy too, in a Vitesse.

I have experienced most engine noises over the years, but this is new to me. If I'd remained in the driving seat I would not have heard it. Oh well, too late now.

 

[Wagger]

I run the car twice weekly now, but it sat for years before my son found it. I drive it on a circular route uphill so that I can roll or get a tow home if necessary. Not needed so far, but I do have breakdown insurance. The 'Ching' is exactly the right description Mathew.

[Pete Lewis]

obscure noises ..............we had a local spitty with some awful sawing noises  expected a chain  & tension problem but it was some PO had  centre   popped the back face of the cam sprocket 

so whilst tight   it did not sit flat   but an alarming rythmical  racket quick zap with the dremmel and silence prevailed 

  and  a  loose flywheels can make  some real peculiar noises at peculiar harmonic times 

Pete

[Wagger]

Thanks Pete. It is definitely front of engine within two cylinders distance. Toolmakers clamp on the throttle cable and 'Stethoscope' in that area confirms it. I did read and listen to a 1500 engine on the forum a while back and the noise ise exactly the same.

My son has almost enough bits to rebuild a 2 Litre engine. As they rev more willingly and it would make all else slightly easier, that would be a solution, AND we would know all about the re-build. His 2500S needs a transplant anyway. I will persevere while this unseasonably warm spell continues.

This has all been a delightful way of ignoring the media and my condition, so time has been well spent.

[Gully]

I have a pushrod and tappet adjuster that stick together on occasions, which results in a rhythmic metallic 'ching' sound on valve 3 (cylinder 2). Just a thought, although I can hear that in the cabin.

Gully 

[Wagger]

Thank you Gully. I can't wait for my wife to go for her swim now and leave me to get on. Just replaced the chandeliers after modding them, not in a 'Dell boy' fashion. It does earn brownie points. Bit like a tesco card.

 

[PeteH]

A lot of years ago. I had a "Strange noise" on a crossflow Ford, Never really affected the performance or anything. It was only when I decided to do a "De-Coke" (remember them?) that the cause was discovered, Rolling the push rods on a flat surface showed one was slightly bent, rectifying that cured the noise. Often wondered if it was just co-incidence?.

Pete

[Wagger]

Pretty sure that Gully is right. I can just hear it from the driver's seat, but I am 20% down on higher frequencies. Can't hear the top octave of my piano at all.

If I use the short broomstick left front of the block, it is loudest there. Can also hear it through the timing cover. I am not going to worry about it any more.

I have used a gallon of fuel in the last week testing various bits out. It has been nowhere. I pumped what was left through to find out how much was left. A mere half gallon! I dare not drive it to the filling station. The main car is a diesel too, dammit! I'll have to buy a ten litre can and fill it.

[Wagger]

Having considered this overnight, I would be very interested to know how Gully observed this phenonena. The pushrod is quite heavy and it would take a lot of suction to stick it to the rocker. Also, the rocker should not be tight enough to withstand the force of the valve spring from returning it. It is far more likely that the valve is sticking, and that would allow the pushrod to drop with a gap between it and the rocker. Now, if the Tappet (Cam follower) was sticking 'UP' then there would be no gap until it unstuck. That would make quite a noise when it hit the cam.

In the 1990's, a colleague of mine had a rogue batch of Tappets (Cam followers) and these stuck when hot, due to expansion, destroying his camshaft and necessitating two engine re-builds. I will continue to observe this as It should all improve with use. Sticky inlet valves can improve with a large dose of UCL in the fuel (Redex). Exhaust valves are more tricky, one needs to dribble penetrating oil down the stems. Difficult with the seals in place.

[Pete Lewis]

have to say in all my years i have never found a sticking valve  ,,,worn out guides  yes  but seized   never 

Pete

[NonMember]

1 hour ago, Wagger said:

The pushrod is quite heavy and it would take a lot of suction to stick it to the rocker.

No, the push rod is really quite light and the top end is a perfect shape for getting stuck either by an oil film or by dings or ridges. In fact it's kind-of-meant to - the tappet/push-rod/rocker combination acts as a single entity so that any gap is taken either at the valve stem or the cam (where a good oil film and a gentle slope make it less harsh).

[Wagger]

OK things must have changed since the 1970's when I owned my 1963 1600 Vitesses. Their pushrods were not light. However, my Triumph motor cycle used tubular alloy ones with hardened top ends. The later Vitesses may have had mods. I still am surprised that a clearance of about 10 thou can result in so much noise.

Rocker box off and rotating by hand may just reveal something.

I had a valve spring break way back then and my old Vitesse had just single springs. That made exactly this noise and it was constant. The piston just hit the valve at TDC, so I clamped it up and removed the pushrod returning home on 5 cylinders. Replaced the spring next day, without removing the head (see an old thread) and it all was fine for another 30k miles until I sold it.

[Gully]

Lifted from my PM to Wagger:

I'll start from the beginning...

Within a year or so of me first having the car, I noticed a noisy tappet that usual adjustment didn't rectify. It was apparent that one rocker wasn't oiling (and hadn't been for a while - the previous owner had caked the ball and socket with copper slip) , so I replaced the rocker shaft, keeping the rockers and pushrods matched (and removed the residual copper slip). Having readjusted everything and run it for a while, I still had one noisy tappet. All were being properly oiled via the new rocker shaft, so I then ran the engine with the rocker box removed and checked the valve clearances with a feeler gauge with the engine running to establish if I had a dished rocker face leading to an oversized clearance. All were okay.

Looking at the valvegear more closely whilst running, it could be seen that whilst the no 3 rocker was moving normally, the socket beneath the adjuster ball was not becoming visible in the blurred motion image I could see. The pushrod socket was holding the ball instead of releasing (pushrod was not rotating, which was another sign). I loosened off the adjuster sufficiently to remove it from the rocker and then tested its fit into the pushrod. It was clear immediately that there was stiction between the two, presumably down to wear from when it wasn't being oiled historically. The oil was then allowing sufficient suction to form to hold the two parts together. The noise appeared to be the pushrod and cam follower tapping together.

I didn't have a replacement rocker adjuster to hand and needed the car for a Club run the following day, so in an attempt to overcome the issue I turned down the adjuster ball a little, mounting it in an electric drill and running it on an oiled sharpening stone. I kept checking the sticking / suction between the two and when eliminated, re-fitted everything. It's generally been quiet ever since, but the previously constant noise does occasionally recur before disappearing again. One day I'll get around to fitting the replacement adjuster I ordered and have in a bag in the shed!

Gully 

[Wagger]

I have answered Gully separately, so this is similar but different.

I understand it now, The ball on the rocker wears a recess in the pushrod with age and poor lubrication. Whilst in compression it 'Locks in'. When the valvespring closes the valve, the rod will be held by this worn recess and slide out more slowly than it would if the recess was not 'Undercut'. Suction also could develop if the oilway is blocked or does not line up. When the rod hits the tappet it will 'Ring' until that rises and traps it again when it meets the rocker. At certain rpm, it could bounce, and at higher rpm the valve spring will throw it down faster than gravity until the valve is closed.

This was a good one, really got the grey matter going. Filming it at various rpm would be very entertaining.

Ended up driving it today before the cold weather arrives. It pulls like a train from 1200 rpm in top. 2000 rpm is giving me 36 mph onhe satnav. That confirms the 3.63:1 diff. Can't wait to get out of the 40mph zone. Maybe next week eh! Then I might just hear the noises.