Under Bonnet rumblings.....?

[Mike J Smith]

After a month or so of owning an S2 I am enjoying the drive/noise more than ever and its grest to have this community to help out or discuss things with if needed!!

I only drive the car too and from work and I have noticed that when I get home and I turn the engine off there is a Bubbling noise coming from under the bonnet?? As I am not mechanically minded AT ALL, what could this be? Is it normal? It doesnt last long and the temperature guage whilst driving tells me its not over heating, just thought I would ask! It has been hot lately and this could be adding to the heat I suppose!

Cheers Mike

[Roy C]

Mike J Smith said:

After a month or so of owning an S2 I am enjoying the drive/noise more than ever and its grest to have this community to help out or discuss things with if needed!! I only drive the car too and from work and I have noticed that when I get home and I turn the engine off there is a Bubbling noise coming from under the bonnet?? As I am not mechanically minded AT ALL, what could this be? Is it normal? It doesnt last long and the temperature guage whilst driving tells me its not over heating, just thought I would ask! It has been hot lately and this could be adding to the heat I suppose! Cheers Mike

They all do that. Well, my S2 has for the past 13 years anyway. I assume it's just the coolant expanding / contracting in the rad, pipes, swirl tank & overflow tank.

[M@H]

They all do that sir... you might find it will dump some coolant if its been recently topped up too..

Cheers
Matt.

[Podie]

M@H said:

They all do that sir... you might find it will dump some coolant if its been recently topped up too.. Cheers Matt.

scares the c**p out of you when you don't know the reasons behind it!

[shnozz]

see this thread www.pistonheads.com/gassing/topic.asp?t=17648&f=11&h=0&hw=spring+cap+gurgling

mine did that and it was coolant in the expansion tank. The reason it was loosing it from the swirl tank was due to the pressure cap getting old and the spring loosing its "spring"

new cap and no more gurgling...

[Mike J Smith]

Thanks boys thought it might be a normal TVR thing just wanted to know for sure?? back to happy motoring!

[John Mac]

My S2 also sometimes has the gurgling indigestion sounds but I have now put this down to simply cooling etc. after a run.
The car was MOT'd yesterday and passed with flying colours, I mentioned that occasionally water was seen to drip out of the overflow, catchment, expansion tank, whatever you like to call it but its the clear plastic one near the bulkhead, the mechanic pointed out that the water level in the swirl tank should be perhaps about 2" down from the top to allow for the expansion under pressure, I'm sure most of us tend to top up to the top of the swirl tank. Iv'e replaced the Pressure cap with a new one but found it necessary to make a new rubber washer as the "metal" seal that was fitted to the new QH cap I'm sure wasn't making a seal. Its all OK now.
Hope the comments may help.

[RichardR]

John Mac said:

the mechanic pointed out that the water level in the swirl tank should be perhaps about 2" down from the top to allow for the expansion under pressure, I'm sure most of us tend to top up to the top of the swirl tank.

The pipe from the top of the swirl tank should be connected to the bottom of the expansion tank on the bulkhead. Therefore, the swirl tank should really be filled to the top as any expansion under heat will be fed into the expansion tank. Likewise, any contraction within the swirl tank on cooling should be replenished by the contents of the expansion tank.

Also, when checking coolant levels you should always be sure to check the swirl tank as well as the expansion tank.

(I'm feeling reasonably knowledgeable on this subject at the moment having just done the drain/refill thing on the cooling system and read all about it in the bible! )

Edited to say that if the normal cap and pressure cap are the wrong way round this can also cause problems; the pressure cap should be on the swirl tank.

>> Edited by RichardR on Thursday 17th July 14:10

[M@H]

RichardR said:

John Mac said: the mechanic pointed out that the water level in the swirl tank should be perhaps about 2" down from the top to allow for the expansion under pressure, I'm sure most of us tend to top up to the top of the swirl tank. The pipe from the top of the swirl tank should be connected to the bottom of the expansion tank on the bulkhead. Therefore, the swirl tank should really be filled to the top as any expansion under heat will be fed into the expansion tank. Likewise, any contraction within the swirl tank on cooling should be replenished by the contents of the expansion tank.

Umm... I think you'll find that all S's are a bit individual.. some like the level 2" from the top of the Swirl Tank, some like it 5" from the bottom.. mine was about mid way... as the Expansion tank is lower than the top of the Swirl tank this causes some interesting "plumbing" dynamics that don't always make sense.

Cheers
Matt.

[RichardR]

M@H said:

RichardR said: John Mac said: the mechanic pointed out that the water level in the swirl tank should be perhaps about 2" down from the top to allow for the expansion under pressure, I'm sure most of us tend to top up to the top of the swirl tank. The pipe from the top of the swirl tank should be connected to the bottom of the expansion tank on the bulkhead. Therefore, the swirl tank should really be filled to the top as any expansion under heat will be fed into the expansion tank. Likewise, any contraction within the swirl tank on cooling should be replenished by the contents of the expansion tank. Umm... I think you'll find that all S's are a bit individual..

That is, of course, a very good point! I think maybe Ted should add an automatic email style disclaimer to the bottom of every posting along the lines:

The views expressed in this posting reflect the poster's experience of their own car and, due to TVR's build processes, may not bear any relation to any other TVR models, even those which are supposedly conforming to the same design.

That should do it!

[John Mac]

Agreed - the TVR and perhaps the "S" series in particular is as individual as their owners.
"If it works leave it alone"
"If it 'aint broke don't fix it"
should probably hold good for most of us !