Running hot at 75 deg+ really bad tapping noise.

[CaptainPolo]

Hi first post and of course it has to be a problem. Fitted new alloy rad/alloy header tank new hoses new thermostat, new coolant with water wetter just in case!.
When engine reaches 75deg+ the engine starts to sound like a sewing machine? Ready bad tapping noises from the head (I think) as engine cools the tapping noise stops.
I have replaced the thermostat again, fitted air bleed valve but still this noise. It started when I flushed the engine?
Any ideas?

Car is a 1963 e-type 3.8 fhc

[christopher storey]

When you say the noises cease as the engine cools , do you mean the noises continue to occur after you have stopped the engine. If so , then it sounds to me like a thermal expansion/contraction noise ( a louder version of the ticking noises all hot engines make when switched off), and is at a guess probably caused by something e.g. header tanks which should be flexibly mounted being too tightly mounted

[Heuer]

Sounds like an air lock to me.

[CaptainPolo]

When you say the noises cease as the engine cools , do you mean the noises continue to occur after you have stopped the engine. If so , then it sounds to me like a thermal expansion/contraction noise ( a louder version of the ticking noises all hot engines make when switched off), and is at a guess probably caused by something e.g. header tanks which should be flexibly mounted being too tightly mounted

Hi Chrisopher, thanks for your quick reply. When the engine is swiched off there is no noise. It happens when the engine runs over normal temp and disappears when the engine returns to normal 72-75 deg in traffic.

Thanks again

[CaptainPolo]

Sounds like an air lock to me.

Hi Heuer, i was thinking that too, which is why I purchased a air bleed valve from Rob Beere racing. Sits in the engine temp sender. Still even with that open I have had a collapsed hose from the Rad to the header tank with no heat going through to the other side of the tank. Fixed that (air blockage)
Now have a rad which now does heat in all 4 corners. Drain tap on engine does have water coming through.
Engine runs fine until it hits 75-78+ temp. It does not seem to lack power it just i slow down because of the noise. Before I added all these nice extras she rarely hit 75+. The alloy rad does have a electric fan built on and it does come on at 70 deg.

Regards Captain Heuer

[CaptainPolo]

Sounds like an air lock to me.

Hi Heuer, i was thinking that too, which is why I purchased a air bleed valve from Rob Beere racing. Sits in the engine temp sender. Still even with that open I have had a collapsed hose from the Rad to the header tank with no heat going through to the other side of the tank. Fixed that (air blockage)
Now have a rad which now does heat in all 4 corners. Drain tap on engine does have water coming through.
Engine runs fine until it hits 75-78+ temp. It does not seem to lack power it just i slow down because of the noise. Before I added all these nice extras she rarely hit 75+. The alloy rad does have a electric fan built on and it does come on at 70 deg

Stuck with no ideas now....its an age thing!

[christopher storey]

It just occurs to me : you are not talking about pinking ( knocking) under load when very hot are you?

[CaptainPolo]

It just occurs to me : you are not talking about pinking ( knocking) under load when very hot are you?

Funny enough its possible.. except the engine starts the tapping noise when its not under load, traffic lights etc and only when the temp reaches over 75+
under load and under 75 its ok?

The noise is very much like pinking..I will get the timing looked at next week.

Thanks again for your help...............

[Heuer]

Does the tapping increase in frequency with the engine revs? Try using a stethoscope (i.e. a bit of hose pipe) to isolate exactly where the noise is coming from. Might be worth doing a compression test to see if one of the valves is a problem. Could be the noise is not related to the new rad.

[MarkE]

How is the fan attached to the radiator? Is there any chance that the blades could be touching something? It seems odd that you only get the noise when the fan is on, but then only under load....hmmmm.

I'm a huge XJR-s 6.0 litre fan as well!! Different sort of fan.....

Mark

[CaptainPolo]

How is the fan attached to the radiator? Is there any chance that the blades could be touching something? It seems odd that you only get the noise when the fan is on, but then only under load....hmmmm.

I'm a huge XJR-s 6.0 litre fan as well!! Different sort of fan.....

Mark

Hi Mark, the fan is attached within a alloy shroud fiited by the alloy rad manufacter. No sign of hitting rad itself. Regarding the XJR-s its amazing how many people look and talk to me now at petrol stations etc.. has the XJS become cool at last?...Tally ho..

[christopher storey]

I have just remembered that a friend had a similar problem which turned out to be a loose tappet guide. It only happened when very hot, at which point the head expanded sufficiently to allow the guide to "float" . A holding down kit cured it

[ChrisC]

I would have gone with the tappet guides moving too... but its real hard to comment without actually hearing the noise.

So I think I would recommend taking the car to a reputable Jaguar specialist and let them run the car up to 75+ to hear the noise and subsequently advise you... might be worth spending a few pounds for the advice.

[CaptainPolo]

I have just remembered that a friend had a similar problem which turned out to be a loose tappet guide. It only happened when very hot, at which point the head expanded sufficiently to allow the guide to "float" . A holding down kit cured it

Thanks for that, i will purchase one from SNG and fit it this week.. I will post up the results...

Thanks very much everyone for your help and advice, I should have joined the forum last year...tally ho............

[CaptainPolo]

I would have gone with the tappet guides moving too... but its real hard to comment without actually hearing the noise.

So I think I would recommend taking the car to a reputable Jaguar specialist and let them run the car up to 75+ to hear the noise and subsequently advise you... might be worth spending a few pounds for the advice.

Thanks Chris, I will purchase one this week and post up the results. its been 12 years since the head weas rebuilt. tally ho.........