4 Psi recovery radiator caps

Ranger

Ranger

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Fellow Frogger
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Sep 7, 2001
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Location
Launceston Tas
I am contemplating connecting a "recovery tank" to the radiator on my `83 505 but I have encountered a slight problem with a replacement rad. cap I want a 4Psi one but the lowest pressure available seems to be 7Psi :(

Recovery caps look just like any other ordinary cap but have 2 rubber seals the extra one is under the top instead of or in addition to the usual brass plate.
The overflow pipe becomes the recovery pipe from the non pressureised catch tank

My present temporary set up that is working remarkably well simply has the overflow pipe into a 2 litre plastic milk carton with a zip tie through the handle blush

Wet sleve engines in general appear to be more prone to "mayonnaise" in the sump and breather than other engines I suspect this is due to the bottom seal of the piston liner leaking slightly ( although I once had a split liner and that gave great blown head gasket symptoms :mad: ) so I think any increase in radiator cap pressure would make this worse

I have been looking at propietary cooling system sealers "irontite" "barrs leaks " etc and reading the directions they mostly state the engine has to be free of antifreeze/anticorrosion
except for one called silva or silver seal . What do other owners use? :rolleyes:

Any knowlegable comments and information on a cap supplier gratefully accepted many thanks in advance. tongue

Cheers Ranger
"The more you prepare the luckier you get"
 
I think 505s made from about 1985 onwards have a recovery tank, so you may be able to buy a 4psi cap from a place that sells Peugeot parts.

Dave
 
Not sure that its the same style cap, Dave, and its much higher rated than 4 psi.

The caps on expansion bottle equipt 505's are screw on , and incorporate a fluid level sensor. They are rated at 11.6lbf/in2 or 14.5lbf/in2 according to Haynes. I took a look at my XN6/sLi cap , but I can't see a pressure rating on the outside. (too lazy to remove it to check the bottom and then have to bleed the system I'm afraid)

Cheers

Rod
 
Rod Hagen:
Not sure that its the same style cap, Dave, and its much higher rated than 4 psi.
Click to expand...
The main thing is that whatever pressure is safe to run on an SLi engine is safe to run on a GR or SR or any other 1971cc Pug engine.

Dave
 
Yes, I'm inclined to agree. Haynes even has a photo of the XN1 engine bay (in a 1985 GR) with an expansion bottle fitted. I'd be wary of fitting something as low as 4 psi. Probably increases the chances of boiling over quite significantly too.

Do the earlier ones have the same style of cap though? Ranger's comments about "the usual brass plate" made me wonder. Sounded more like a "flange" type cap. The one on the sLI (and the one shown in Haynes) are both plastic , screw on varieties which wouldn't fit on a "flange" fitting type radiator filler hole.

Cheers

Rod
 
On the same subject, the easy way to fit a "recovery tank" on 403's and 404's was simply to cut the drain pipe from the radiator overflow , hook up a plastic tube, and direct it to an expansion bottle. No need for special caps.

Cheers

Rod
 
Just out of curiosity (i know nothing! - to quote Faulty Towers), why are "recovery" or "expansion" tanks needed? All my parent's cars have always had one, but my GR is the first I've seen without one...

should I get one too? :confused:
 
Thanks Dave and Rod
what I described in starting this topic is a basic recovery system as related by Rod for 304 and 404 this relies on the brass plate providing the top seal to create the cooling vacuum to do the reeovery, this is ok up to a point, but it is not the best seal that is why I am trying to locate a proper 2 rubber seal recovery cap in the "classic" style.

I don`t want to change the radiator etc. for one from a later model.

4 Psi is the manufactures recommendation based on the owners glovebox handbook for the 504
( page 35 )the 505 is basically the same setup except for the bi-directional cross flow radiator in the 505.

I believe this low pressure ( by current standards ) is so the bottom cylinder sleeve seals are not too greatly stressed, any small quantities of coolent passing through goes straight into the sump and re-appears as mayonaise :mad:

So although increasing the cap pressure will increase the boiling point,overheating is not a problem ,I believe it would only make the mayo problem worse. :eek: :mad:

so three questions remain.
1) Is there a 4Psi 2 rubber seal recovery cap made ?
2) What coolent additives/sealers are other people using ?
3) Anybody out there have the 505`s handbook rad cap pressure ?
And Nick, hang in there read and learn this is all about "Sharing the knowledge"
Something to ponder,
cheers Ranger.
 
ranger:


4 Psi is the manufactures recommendation based on the owners glovebox handbook for the 504
( page 35 )the 505 is basically the same setup except for the bi-directional cross flow radiator in the 505.
Click to expand...
Later 504's had a 12lb/sq in cap though Ranger. (see Autobooks 504 manual p162) I suspect this is what was probably originally fitted on the 505.

The "mayonaise' issue with Peugeots CAN be related to a bit of seepage around the liner seals or head gaskets, but its also often related to poor breathing (a "positive feedback" situation - mayonaise adds to poor breathing and vice versa), low engine operating temperatures (faulty or missing thermostats) and short trips. Regular oil and filter changes help too -see page 42 of your 504 owners manual!

Cheers

Rod
 
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