3,5 MK4-ticking noise only when engine is hot and over 1400 rpm

(Rob Reilly) #21

Glad to hear you found the noise.

Your rockers should not have the clip springs under the rockers that my '38 car has. That was eliminated in mid '38 when they began to put C.517 springs and C.519 collars on the pushrods. However, my Mark V does not have pushrod springs either, never did. Perhaps some Mark IV owner knows if the pushrod springs were eliminated before the end of Mark IV production?

The C.561 Ball Pins and C.379 Lock Nuts are the same for all pushrod engines. Be aware that the thread is British Cycle thread and not British Standard Fine. The threads on the ball pins are very easily damaged, which is probably why one of yours was replaced.

I suspect you only need to replace the one ball pin and lock nut. Worcester Classic Spares in England may have the parts, or Cordell Newby in the USA.

(Ed Nantes) #22

OK tappet adjusting screws. The originals had a design weakness. The BSC thread is very fine and the screws were case hardened. Unfortunately the depth of hardening from both sides of the thread meant they were ,in effect, through hardened. And, so brittle. And often there broke pieces off in situ and jammed. Sometimes one could not wind them through[ the normal way to remove them] but sometimes it worked to cut the ball off with an angle grinder and try to wind the thread out backwards.
A few years ago i had a batch made, but being cuning , I had the thread masked off during the heat treatment… easy to do. Which meant the ball was hard but the thread was just tough and retained tensile strength.
These all worked well and I had hundreds made. I though I might still have some, but from memory i sold the remainder to Simon Whitworth at Worcester classic Spares. So he would be the best bet. I do have a handful of the half nuts , new , if anyone needs a few.

Reading about the loose screw in Helmuts tappet, I suspect someone has used an MG TC as a replacement. When I did the batch an SSowner who also worked on TCs said" waste of time, you can use MG TC’ as though MG TC screws were lying round everywhere[ and for 4 cylinders too] But checking the MG doesn’t have exactly the same thread. . From memory 1 TPI difference and fractionally smaller. { Probably metric as MG got a deal on cheap metric threads around the time of the TB/ TC. But this meant all the load was on just one turn of the tread… And I know from making pushrods, MG are an odd size ball.

Really the whole rocker gear needs to be dismantled and cleaned and checked and new wicks put in and the shaft condition checked. And one would like to see lots of oil running down the pushrods when idling.

(Helmut) #23

Yes the thread of some of my ball Pins is also damaged. And as I told before One ball pin is wrong with a Little bit different thread. Maybe it is the MG-Part as you said. My engine number is S 2264 and in the certificate of the Jaguar Heritage Trust stands that it was built 1st January 1948. Maybe somebody knows something more of my push rods without the springs. Some Fotos with the different ball Pins.


(Helmut) #24

Another picture

(Ed Nantes) #25

You can leave off those springs. Ian Mullins has new adjusting screws and Is going to email you.

(Helmut) #26

Thank you very much !

(Rob Reilly) #27

I didn’t know Ian Mullins had email. Can you send me his contact info?

(Helmut) #28


Write me an Email and I send you the adress


(Ed Nantes) #29

Yes his carrier pigeon died early in the year. Delicious though.

(Helmut) #30

Today I got the ball Pins, rockershaft and bushes from Worcester Classic Parts. When I look at the ball Pins I see that the balls look all a Little bit different. Some are like a ball and some have a flat head. I think all ball Pins should be the same ? Does somebody know more about this ? Make the differnt ball Pins maybe noise ?

(Ed Nantes) #31

the flat shouldn’t make any difference. The flat will hold alittle oil, but the load should be taken over the whole curvature of the bottom half.

(Helmut) #32

I have replaced with a new rocker shaft und new bushes and new wicks. Also the ball Pins are all new but I have still the ticking noise after 15 minutes ! Oil is coming down the push rods. The engine does not smoke and runs very fine - but only for 15 minutes. I have no springs on the push rods. The oil pressure is after start 60-80 then 40 and goes down. When the noise beginns it has 30-35 and after 30 minutes when the engine is hot it has only 10 /800 prm and max. 15-20 / 2500 prm. I think this is not enough. At 800prm the ticking Sound is nearly off but at 1500-2000 it is very loud to hear. I think the noise Comes from the cylinder head - had somebody Maybe the same Problem ?? Is it the Piston pin ?

(Peter Scott) #33

Possibly. I have a small end that taps on cold start-up but it gets quieter as the oil circulates and warms up. I changed the oil recently with fully synthetic rather than just part synthetic and it is quieter on cold start-up now, presumably because fully synth has better retention properties.

Your oil pressure readings would suggest worn bearings in general.


(Ed Nantes) #34

yes , should be about 20lb at idle when hot, although with modern oils mine is over 30lbs.

(Peter Scott) #35

Yes, I know we love driving these old cars to experience how they once were but using mineral oils instead of synthetics is just masochism. Call me a non-purist if you like but I also have no guilty feelings about using a postwar oil pump and MkIV twin leading shoe brakes instead of the single leading SS ones.


(Roger McWilliams) #36

If sound is from cylinder head height, then valves and rockers are the leading places for noise issues. If I read the full thread correctly, it was mentioned that rocker clearances were 0.012" and 0.015" when warm. That would not be correct setting, the 0.012" and 0.015’ clearances are for cold engines.

Oil pressure low issues are suggestive of lower bearing clearances being a bit large. The tapping noises from piston and crank bearings have different sounds compared to rockers and also are lower in the engine. What to do about such matters may depend on how you want to use the car and how bad the sounds are (throwing a rod would not be a desired motoring experience).

(Helmut) #37

The clearances is 0,12" and 0,15" COLD - I know