swan neck question

[mhardy]

At the moment we are putting back the engine in the 350i '90.

the swan-neck is not in a "very good shape" and we were wondering why the fillercap at the top is for?

only for filling coolant when the system is compleet empty or ???? we would like to leave that cap and make a new swanneck.


Cheers from the Netherlands and hope to see a lot of you wedge'ers at our continental meeting ZOLDER!!!!!

Matthijs Hardy


again:sorry for my broken english

[Rus Wood]

The swan neck is where you should always top up, but do it with the correct amount of water in the header tank and the cap on.
The swan neck should have a plain (not pressure release) cap and the header tank should have pressure release.
Regularly check the top-hose where it passes under the front of the bonnet because many Rover engine cars suffer from the bonnet scraping the hose as it opens. I have modified mine to avoid this problems.

[Gerry Attrick]

Rus Wood said:

The swan neck is where you should always top up, ...

But why should you have to top up at the swan's neck?? Surely, the system should allow you to fill at the bottle and drain into the remainder of the system like other cars.






Yes, I know, TVR's are not like other cars!!

[jvaughan]

Because the swan neck is the highest point on the engine. The cooling system in the Rover V8 is very High (where as on normal eurobox's the expansion tank is the highest point).
On a V8 you need to vent the air that would get trapped at the "top" of the cooling circuit ... hence the swan neck

[Gerry Attrick]

Jason, thanks for the clear and concise reply. I've asked that question many times but it's the first time I've had a sensible answer.

[jvaughan]

Gerry Attrick said:

Jason, thanks for the clear and concise reply. I've asked that question many times but it's the first time I've had a sensible answer.

Thanks .. T'was my first

[dickymint]

Just to put a spanner in the works on this one.
I was having a look round the engine bay on the SEAC yesterday and found:
1) expansion tank is highest point (i found this out when i was viewing the car prior to purchase as coolant pi"@ed out onto Steves carpet when i opened the swan kneck sorry Steve!
2) I have an extra tank under the expansion tank!
3) Found a TVR sticker explaining how to fill the system.

Took a photo of sticker to post as I thought it would be usefull, but its not readable(no macro).

[DJC1001]

I am just refitting coolant hoses and swan neck. Agree swan neck and expansion tank are about level.
The swan neck gives an easy / quick fill for the engine but more important air bleed from the highest point on the engine. Air naturally goes uphill so will will not necessarily find its way out via other vents.
I dont think the swan neck is vital but some method of venting at this high point is vital. If air remains in this area an engine may run hot for no apparent reason.
Some swan necks on later cars just have a piece of hose with a bolt stuck in the end.
The overflow tank below the expansion tank catches any water from the expansion tank which should return when all cools down. One set of instructions I found recomended the overflow tank should be half full.

[Gerry Attrick]

Since my last post I've made a few investigations. The mid fill level on my expansion tank is level with the top of the filler on the swan's neck, but the swan's neck continues upward after that point. This suggests that the highest point of the engine coolant system is higher than either of the filling points for coolant. If that is the case, and my car is no different from others (but, are any two TVRs the same???), it will be impossible to fill the cooling system completely, with the engine stopped. I've seen elsewhere in postings on this site that the recommended filling procedure is to fill the swan's neck and the expansion bottle with the engine stopped; run the engine at a fast idle and add water to the expansion tank. The swan's neck will empty as the coolant is pumped around the system, until water added to the expansion tank fills the system (and presumably that volume above both fillers). With the engine still running, fit caps to the swan's neck and the expansion tank in that order. Stop the engine.

If there are no leaks the system, including that above the fillers will remain full. If you have a leak, any air will find its way to the top of the engine above the fillers, and you will need to repeat the operation. On my car, the swan's neck filler is worn and, although it seals when hot and pressurised (no water leak outwards) air gets into the system as it cools down. I'm off today to get a new fitting to the swan's neck.

Incidentally, the owners manual merely proposes topping up once a week, and implies using the expansion tank as a filling point.

Is this total b**ll*cks??? Any comments from the more knowlegable owners more than welcome.

[streaky]

This clearly shows that the top of the expansion tank is much higher than the swan neck on my 390SE:



The normal feed to an expansion tank from a filler cap is plugged by a bolt:



And there's this in the swan neck:



(Appologies for the curling under-bonnet insulation.)

Streaky

>> Edited by streaky on Friday 14th May 14:51

[grady]

On my 280, the expansion tank is the high fill point about 4-5 inches higher than the swan neck fill point. However, above both, at the very top of the engine, is a plastic fitting that connects smaller hoses running between the engine and the expansion tank.


Thus, after a major drain caused by changing the thermostat at the bottom of the engine, I re-filled via the swan neck, then via the expansion tank. Finally, I started the engine and once I felt warm water circulating, loosened the highest hose filling, bleeding out the air - replacing with water added at the expansion tank. Also had the heater turned on.

Seemed to work. Grady

Edited to try to add picture

Sorry all, offending picture removed



>> Edited by grady on Thursday 15th April 16:56

>> Edited by grady on Friday 16th April 14:39

[streaky]

grady said:

>> Edited by grady on Thursday 15th April 16:56

Didn't work - Streaky

[grady]

My first try at posting goes down as a dismal failure

[HeyAndy]

I agree with Gerry. You need to undo both caps, fill the swan and header until overflowing and run the engine until the thermo opens up. The level will drop off thereafter. You then need to fill the swan until the water levels off at the top - it will be hot but more importantly if there is air in the system it will bubble up at the swan neck until its clear, you also need to keep topping up the header while this happening. When there are no more bubbles - cap off the swan and the header making sure the header has the required amount of water.

Another thing to make sure is that your fan cuts in when its supposed to. If you've done the job correctly, the the temp will drop when the fans cut in with both caps on.

[jmorgan]

Er....ah.....I have been told to check the fluid level in the expansion tank and make sure the water is up to the neck in the swan neck.....seems to work.....

Also on some cars the heater hoses are higher. I have seen a plumbing jobbie to bleed for that. Sort of like a rad bleed thing.

[adam quantrill]

For my part I only ever fill via the swan neck cap after a major loss of fluid - an engine rebuild, rad replacement etc.

Once I have filled up via the swan neck cap I seal it down with some blue hylomar for good measure.

Then I just use the expansion tank to maintain the fluid level. Tnis method has worked for me for 10 years (is it really that long ;^? )

- Adam

[streaky]

grady said:

My first try at posting goes down as a dismal failure

Does anyone else get the effect I experience when entering this thread?

Caused, I believe, by grady's (failed) attempt to post a picture, I get a log-in prompt for "caycee.us".

grady - I suspect that you have posted a link that requires a log-in and suggest you check what the URL should be to allow public access.

Streaky

[redcar]

streaky said:

grady said: My first try at posting goes down as a dismal failure Does anyone else get the effect I experience when entering this thread? Caused, I believe, by grady's (failed) attempt to post a picture, I get a log-in prompt for "caycee.us". grady - I suspect that you have posted a link that requires a log-in and suggest you check what the URL should be to allow public access. Streaky

Yep. I also get "caycee.us".coming up.

[HeyAndy]

A good seal on the swan is also important too...!

[dickymint]

This is the filling instructions on the SEAC.
http://community.webshots.com/scripts/editPhotos.fcgi?action=showMyPhoto&albumID=128070717&photoID=135236073&security=EhegPB

Its more readable if you download it and open.