Omega Owners Forum
Omega Help Area => Omega General Help => Topic started by: GrahamK on 29 September 2025, 16:27:07
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Hi all,
I've recently been re-commissioning the Omega after a year or two off the road.
Firstly it runs perfectly. However, I had noticed that it was loosing a little bit of coolant externally before I had parked her up. I did need to put a bit in when I got her going (perhaps one litre) and i ran her up to normal running temperature yesterday, on the drive, until the fans came on and then went off. All seems OK.
However, this morning I notice the header tank is creamy black and obviously has a lot of oil in there. The engine oil level has dropped about 5-10mm, but does not look like there is water in it.
The oil filler has a sheen of mayo in there, but nothing excessive and what I would expect from just an occasional brief run.
Having done a search on here, oil cooler seems a good bet, but I wonder if folks could let me know if this seems sensible considering all the things I have reported here.
Next the question of where I might get a new cooler from? There are not too many, if any available that I have yet found. I take it the part number is the same on all the V engines?
I have a spare engine that was running. Is it a crazy idea to refit a used one?
Does anyone have a oil cooler on the shelf that they didn't end up using?
Regards,
Graham.
p.s. Car is 2003 2.6
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Hi mate,
I don't really know about the troubleshooting of this particular case. But I can give you some info about the oil cooler.
I replaced mine (preventive move) by a stainless steel one from ACS (Advanced Cooling System), which is Ukrainian supplier for a lot of Opel/Vauxhall parts.
https://acsparts.biz/en/maslookholodzhuvach-90412391-opel-saab.-nerzhaviiucha-stal/
The part is 113€, costs near 150€ after all customs and taxes.
It comes with both new o-rings. Then you need 4 new bi-material rings and 4 new metal rings for the 4 banjo bolts of the cooler itself and the cooling bridge.
My genuine one is still like new but it's the aluminum one, so I don't want to propose it to you :D it could fail at anytime
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Thank you Valentin.
Much appreciated. It looks different to what I expect. I thought they were flat (a bit like an air cleaner element). I've not seem one, just photos.
Graham.
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The original one is flat
(https://cdn-product-images.revolutionparts.io/assets/d163e09e1523eb87b7b14f5b35648e7b.webp)
If you look on the 3rd picture on ACS website, the shape is a bit square for the cooler to fit correctly in the block :y
You can take a look at my topic here https://www.omegaowners.com/forum/index.php?topic=151703.msg2058124#msg2058124 but it seems the pictures are gone :-\ ;(
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Thank you again, that explains it perfectly.
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nothing wrong with fitting a used one in my opinion.virtually all omegas will be fitted with a used cooler ! same as any other used car and i beleive all the later coolers were stainless anyway ?
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Of course, but Graham's Omega is a later one, assumed with a stainless steel one, and if it's broken it means any other later one can do the same because the part has maybe some weakness from its thin design.
Regarding the amount of work to change it, better to change it by a model made with a strong thick tube, and don't come back to it in 5 years :y
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I think most were stainless, only very early ones weren't
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The one removed from my 96 is aluminium :y
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What are OOF members doing about replacement washers for all the pipes going to and around the cooler?
I’m guessing they’re discontinued at Peugeot, I mean Vauxhall?
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A dowty washer is a dowty washer surely :-\
Find a decent plumbing supplier and take an old one along with you ;)
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Timing is everything and I do need to get the old girl back on the road, so waiting for a delivery from Ukraine is not ideal. I have a spare engine and I'm going to have a practise by removing the oil cooler in that one and replacing mine. Mine is a late car, so should have a S/S cooler, but I don't know if the coolant has been kept in good nick or not. I will have a look at flushing agents to try and remove as much oil as possible. Thank you for confirming that some are Dowty washers, but I'll replace like for like, depending what I find.
Cheers all.
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A dowty washer is a dowty washer surely :-\
Find a decent plumbing supplier and take an old one along with you ;)
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Fair comment.
I’d always like the correct Vauxhall part in these circs.
But as mentioned might not be available so may have to do that.
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Ps.. though I’ve never had to do this job I often look at those two unions above the oil filter and they just don’t look like they’d come out 🤣🤣
Anyone ever had issues with them? I suppose absolute worst case scenario you’d end up chopping the pipe above the nut and getting a 6 sided socket on it. Just wondering if anyone ever had issue?
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Unbolt the filter housing. It's a single hollow bolt holding it to the block :y
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It’s cool DG cos I’ve already done the filter conversion.
Was just curious about any issues anyone ever experienced.
I don’t need to do this job. I’m just bi-curious 🥰
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Had heard >:D
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🤣
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Ps.. though I’ve never had to do this job I often look at those two unions above the oil filter and they just don’t look like they’d come out 🤣🤣
Anyone ever had issues with them? I suppose absolute worst case scenario you’d end up chopping the pipe above the nut and getting a 6 sided socket on it. Just wondering if anyone ever had issue?
As per above, filter off,, crows foot spanner, tighten slightly, then undo.
Never had an issue to date with them. :y (probably done many tens of them over the years, including Opti's whilst it was on his drive!)
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Great to know, thanks Mark 👍👍👍
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A used, stainless cooler, is likely to be fine. You'll need to source dowty seals, coolant bridge seals, union-to-cooler seals, grey RTV, cooler-to-plate o-rings, oil filter housing seal etc. But, a stainless, used cooler will be fine.
The old style coolers (which corrode) have protrusions on the top of the cooler radiator - whereas the stainless ones are completely flat on the top edge.
Here is the old stlye, known to corrode:
(http://images.omegaowners.com/images/guides/V6_Oil_Cooler/V6OC8.jpg)
Here is the newer, stainless type, flat on top:
(https://i.ibb.co/dwBGT6wL/new-style.jpg)
And, food for thought - I am currently in discussion with a European firm, about a bulk buy of these:
(https://i.ibb.co/Y76zyyMS/IMG-1763.jpg)
Ultimately it's almost impossible to get a new, original cooler these days (or they are astronomically priced)... so worth at least exploring potential other options / viable alternatives :y
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Hi all,
Continuing with this thread that I started a little while ago.
I have not found a UK source for an oil cooler and so today I have removed a cooler from a spare 3.2 engine I have. By definition, a late engine, surely.
Looking back at the pictures posted by James my replacement one looks rather like the older type. It does look S/S though. The GM part number on it is 90572067.
Without any other tenable solutions, I am planning to re-use it, for now.
Looking at the parts I have on the bench I wonder if someone would be kind enough to error check my thinking here: -
Firstly, I have the banjo bolts that secure the metal pipes to the top of the cooler. These have what looks like an aluminium washer above and below the banjo. These are available, but could I re-use these?
Next, I have the pair of "O" rings that seal the cooler against the bottom of the cover plate. These are circa 28mm diameter but are totally flattened. I have no idea about part numbers for these, or if I could use a suitably sized O ring from a multi part (generally pretty cheap) set.
I have some Vauxhall grey sealant. I can also see from the exploded parts catalogue view that there is thread lock used somewhere in this assembly. Does anyone know where?
Finally, I have what I think are Dowty washers securing the Banjo bolts that go through the coolant bridge. One above and one below, so I need four here again. These are buggered.
Measuring them, they are 23.85 mm OD, 1.6mm thick and approx 16mm ID. It is difficult to tell as they are pretty ragged. The diameter of the banjo bolt is 15.8mm OD, near the shoulder, under the bolt head. I'd have thought that the rubber part of the washer should be a little less than the diameter it is sealing against, but I've not specced any of these before. Any idea which ones to order?
Any other tips or advice would be much appreciated.
Regards,
Graham.
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Those flat 'seals' are the dowty washers.
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I would try to source dowty washers if possible, in my experience reusing old ones does tend to leak, particularly if the old ones are original.
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Measuring the flat steel washers with the captive rubber/nitrile inner (these are the Dowty washers, yes?) and comparing the size I have with suppliers tables means they are most likely M16.
The rubber only rubber rings that look exactly like flattened O rings I do not have a part number for. (they came with the oil cooler apparently)
I'm not sure if it is a specialist seal, but considering where it is, if I take a gamble and the bloody thing leaks, I'm back where I started.
I note what Doc said about the flat rubber seal being a Dowty washer. Is that a different type of Dowty washer, or are we just lost in translation.
Any help much appreciated!
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Measuring the flat steel washers with the captive rubber/nitrile inner (these are the Dowty washers, yes?)
Correct
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There is a solution like I said before, the part made by ACS in Ukraine is perfect. It's a bit expensive but looking at the amount of work it needs to be replaced, better to go for this aftermarket solution IMO. AND it comes with the 2 O-rings that you found flattened. They actually are O-rings and made in NBR, same material as any o-ring made for automotive industry :y
https://acsparts.biz/en/maslookholodzhuvach-90412391-opel-saab.-nerzhaviiucha-stal/
https://www.omegaowners.com/forum/index.php?topic=151703.msg2058124#msg2058124
As for the dowty washers for the coolant bridge banjos, again, take the old one and a banjo bolt with you and go to a truck repair shop. They can find a model that is close to yours. Never reuse the old ones.
For the all metallic washers on the oil banjos, same you can ask the truck shop. In my case they gave me 4 new ones but arrived at home I found out one of them was a bit smaller and didn't fit. I reused an old one after a good clean and 400 sandpaper. It works fine.
Grey OEM Vauxhall/Opel sealant or ELRING DIRKO 70ml GREY Gasket Sealant for the plate.
Finally, to have peace of mind about any leaks, I put a very thin layer of Loctite 5923 on each face of the 8 washers and on both contact faces of the 2 O-rings. Don't put too much on those for the coolant bridge, because they need to make electrical contact for the temp sensor's ground. No RTV, only suitable Loctite 5923 which is a permanent sticky/soft mixture that never falls and never tears apart.
Take care of the peripheral components (wiring looms, tubes, connectors) and everything should be fine :y 8)