Omega Owners Forum

Omega Help Area => Maintenance Guides => Topic started by: razzo on 27 October 2008, 21:27:44

Title: Pressure testing cooling system
Post by: razzo on 27 October 2008, 21:27:44
after reading a few posts about leaks in the cooling system you may want to have a go at detecting the leak yourselves. Pop down to your local tyre dealer & ask him/her for an old inner tube & a tubeless tyre valve, you will also need some Epoxy glue, a pressure gauge( got this from halfords) & an old tank cap.

First off take out the seal in the tank cap, be gentle with this as you need to use the seal later


cut open the old inner tube you got from the tyre dealers & using the plastic valve you removed from the old cap draw round the valve & cut out, so you have 2 rings the same as the one shown below


cut out

then drill a hole in the old cap slightly smaller than the diameter of the new tyre valve, i drilled this hole with a 12 mm bit, turned it upside down, dabbed some glue in the 4 grooves at the base & fitted one of the rings cut out earlier, a smear of glue wouldn't go a miss all around where the ring sits


then place a smear of glue on the ring in the cap & fit the second rubber ring, then the original ring to the cap, this needs to be an airtight seal so if you haven't used too much glue, place some plastic film over the tank, refit the cap & let the glue set. Be careful here as getting Epoxy glue in the cooling system will not earn you any brownie points. Once the glue has set, remove the cap, bin the film & now put some glue in the groove of your new valve, pulling it through the hole you drilled in the cap so it looks like so


if you want to you can put some glue around the valve on the inside of the cap but don't go mad & don't block up the hole


leave the cap upside down so it sets evenly, once it has you can now use it to find that elusive leak. Refit the cap when all is dry & with a full coolant tank pressurise the system to 15 psi (i used a bike pump with a shrader valve) & the gauge from Halfords


When i did this i found a very small nick in a hose connected to the coolant bridge


i also found a leaking oil cooler cover plate which one garage diagnosed as HG failure & another as a porous block (Muppets)

So once you are sure the cap is airtight, is not leaking & is holding pressure all should be well, if not & pressure drops you may find the leak shows itself, this should only be carried out on a COLD engine.
If the leak is at the back of the engine as mine was you may need to remove the plenum, injectectors & injector bridge as this will give you a better view of coolant pipes, coolant bridge & oil cooler cover plate. If you clean up this area & ensure it is dry as you pressurise the system hopefully all will be revealed.
Hope this is of some help & good luck

Steve  :y

On V6, this becomes even more useful if you block the coolant pipes to plenum, and remove plenum and inlets so you can see in valley, or simply turn the plenum upside down and laying it on rad.

Do not pressurise beyond 16-18PSI