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1

Omega General Help / Re: 1999 Omega 2.5 v6 Elite - failed oil cooler

« on: Yesterday at 17:01:47 »

UPDATE ON DRIVING WITH OIL COOLER BYPASS AND NO OIL COOLER

Been driving in the recent hot weather and the water temp has not gone above it's previous usual running temp of 95 degrees (on the gauge).

Currently no adverse effects of having no oil cooler/heat exchanger, even in the hot weather, though as the car is a 2.5 v6 and no towing is involved, that was suggested as the likely result on the other forum, ABS.

Hopefully that will give some comfort to others having difficulty finding a new oil cooler (though I have recently seen one in S/S mentioned on this site), and who might otherwise be reluctant to go the bypass route.

2

Omega General Help / Re: Oil cooler pipe replacement

« on: Yesterday at 16:39:10 »

When my oil cooler failed last winter and I could not obtain a new one I opted to remove it completely and fit a bypass hose joining the two connections, by the oil filter, to maintain circulation but without cooling.
Got the pipe made up by Pirtek in Basildon. They did it without a pattern as it was a non OE variation. Pirtek in Basildon were great.
Apparently you can now get new SS oil coolers (see recent listing on this site). I'll leave mine bypassed as even in the recent hot weather, the engine has not been getting hotter than 95 degrees, so happy with that FTTB.

3

Omega General Help / Re: Radiator Drain plug leak - Omega v6 2.5 1999

« on: 14 June 2025, 16:04:49 »

Thanks for the link to the ebay listing. Just bought it.

It looks the same as the used one on ebay for an Agila, that they want £11.00 for!!
Part of the issue with searches seems to be what you say you are looking for and if you call it the wrong name, it won't appear.

Anyway, thanks for taking the trouble to search it out.

4

Omega General Help / Radiator Drain plug leak - Omega v6 2.5 1999

« on: 14 June 2025, 12:48:30 »

An irritating, and increasing frequency, drip has started from the small outlet at the side of the radiator drain plug, which is located at the bottom L/H side of the rad.
There is no further tightening to be done on the red knurled (plastic?) knob just below it, so I assume one or more of the O rings has failed.
Problem is I cannot find a replacement drain plug anywhere (though not tried Vauxhall dealer yet). It looks like the sort of part that would be common across a number of cars, so if anyone knows a part number, that might help source a new one.
Otherwise I'll have to try and cap off the drain tube with a push fit stop end, if there's enough room.
My preference is to buy a new one.
Don't particularly want to remove the drain plug and replace the O ring(s) as the drain, once loosened, seems to be held in place by something that stops it coming out completely, so I don't want to force it out and potentially damage something in the rad.
Suggestions???

5

Omega General Help / Re: V6 Oil Cooler

« on: 01 March 2025, 00:44:10 »

unfortunately about 3 months too late for me as I fitted a bypass pipe when my oil cooler leaked into the coolant! However, it seems to be a regular failure point, so will be useful to someone.... soon.

6

Omega General Help / Re: 1999 Omega 2.5 v6 Elite - failed oil cooler

« on: 30 January 2025, 11:14:41 »

Yes we removed the oil cooler completely. Had we left it in situ but disconnected from the oil supply, there was the obvious risk of water getting into the oil cooler via the leak and then out of the two large pipes that that took oil to and from the cooler, so we would have had to block those too. As the thread on one of the connections was stripped, making a water tight connection would have been problematic, so why bother for a non functioning oil cooler?

We removed the cooler completely and sealed up the two large holes in the top plate with a heath robinson concoction  of penny washers over the holes on each side with a 12 or 14  mm nut and bolt to hold them in place, with plenty of mastic both sides and between the washers, to hopefully stop leaks from the valley where the cooler used to sit. THe top cover was also sealed before its bolts were tightened.

No signs of water leaks or water loss so far, so appears to be working. With the cooler removed then the water will flow unrestricted into the valley and out again, so this faster flow of coolant may contribute to the slower warm up. But I'd rather it run cooler than hotter, and the weather has been cold, so that might be responsible. I'll know as the weather warms up.

7

Omega General Help / Re: 1999 Omega 2.5 v6 Elite - failed oil cooler

« on: 29 January 2025, 11:09:12 »

There are no oil cooler connections to seal. We detached the two oil pipes that ran from the block (by the oil filter housing) up to the cooler and back again. We replaced them with a hose that links the two outlets on the block together, so the oil just comes out of the block and back into it again.

Not really concerned about the Stat being bunged with oil. What surprised us when we removed the header tank (coolant reservoir for the pedants amongst us) was that although it was full of oil, no oil appeared to be anywhere else in the cooling system.

After fitting the bypass and running the car for about 20 mins there was a slightly oily residue in the top of the header tank, so we removed it again and cleaned it out. Upon reinstallation, no further oily residue has appeared, so I really cannot work out how so little oil managed to get circulated around the cooling system given the header tank was completely full of oil and there was oil in the valley that the oil cooler sat in. Not sure how much oil had been lost but it had been at the full mark on the dipstick when I last checked it, but was only just touching the very bottom of the dipstick after the leak was discovered. I had only done about 15 or so miles since I last checked the water and oil levels which were both normal, so it may be, as someone suggested previously, that I caught it early enough to stop it getting circulated around the cooling system.

8

Omega General Help / Re: 1999 Omega 2.5 v6 Elite - failed oil cooler

« on: 28 January 2025, 10:38:01 »

A heat exchanger it may well be, but as I could not find a new replacement (nor 2nd hand at the time), if I hadn't done the bypass, the car would still be sitting partly dismantled in my garage and undrivable, waiting for a mythical oil cooler, whereas now it's been MOT'd and is back on the road.

9

Omega General Help / Re: 1999 Omega 2.5 v6 Elite - failed oil cooler

« on: 27 January 2025, 09:34:00 »

Been driving it a bit now and the burning oil smell has gone and no sign of oil loss either. It is noticeable that the engine takes longer to warm up without the oil cooler and so far only seems to get to about 92 degrees on the gauge, whereas it used to run at 95 degrees and would warm up quickly.

However, it has been cold recently.

10

Omega General Help / Re: 1999 Omega 2.5 v6 Elite - failed oil cooler

« on: 15 January 2025, 18:51:20 »

After we did the oil cooler bypass put it thru the MOT last week and it passed with just one advisory for one rear tyre, which I'm planning to replace anyway.

However, on the journey back from the MOT station we could smell burning oil. Nothing coming out of the exhaust (smoke or oil) and no obvious leak from the new bypass hose, so I'm hoping it was some of the oil from the header tank (which spilled over the engine when we removed it for cleaning) that has found its way onto the exhaust manifold and is burning off as the exhaust gets hot. No loss of oil from the sump as it's still full on the dipstick so hoping the smell will go in a couple of weeks.

Got a bit of a shock when I checked the mileage between MOTs in the last year. Less than 400 miles (not a typo) for about £2500 in repairs. At least I'm not spending much on petrol!

Have to see if it goes longer than 4 weeks now without another issue, otherwise the old girl may be on the way out. I can justifiably spend more money on my old Rover P5B to get that back on the road as it will have a value in excess of £10K when its finished whereas, with the omega, I seem to be just tipping money down the toilet!

11

Omega General Help / Re: Opel Omega V6 2.6 Timing Belt

« on: 24 December 2024, 00:14:39 »

I changed mine in the summer. It had done 47000 miles but the belt was last changed 20 years ago, so I wasn't prepared to take the risk. When we took the old belt off it was still in vgc. However, the belt around the LH cylinder bank cams and tensioner was a bit slack and they do say it is the tensioners that are the weak link, not so much the belt, so probably best to have changed it. ONly cost me £450 plus the belt kit and water pump as I had a special deal with my mechanic. However, it was the first one he'd done on this engine (mine was the 2.5 v6) and he said not to ask him to do it again as it was a nightmare, even with the locking kit!

12

Omega General Help / Re: 1999 Omega 2.5 v6 Elite - failed oil cooler

« on: 27 November 2024, 11:33:41 »

In response to Stu.C, there is no oil cooler.

THe bypass pipe made up by Pirtek consists of an M18 x1.5 coupler (threaded at each end) in each of the connections to the block by the oil filter housing. THese are then connected to a flexible hose via 2 crimped connections with nuts that attach to the other end of the coupler. THis will maintain the flow of oil out of the block and back again without going to the (absent) oil cooler.

I'm not concerned about the overheating of the oil in the engine as I don't tow and tend to do journeys of no more than 40  miles at a time. Only time will tell if this set up works without overheating, though it should be okay during the winter, and I wanted to get the car back on the road asap without having to fit an external oil cooler with the associated piping etc.

Posting a pic here is too much of a faff, but if you want to see a picture of the hose (not yet fitted) send me a PM with your email address and I'll email you the pic.

13

Omega General Help / Re: 1999 Omega 2.5 v6 Elite - failed oil cooler

« on: 25 November 2024, 13:40:19 »

Got the two cooler pipes out on Friday where they attach to the block.
On measuring the O/D of the male connection that screws into the block, it came out as 17.90 mm on my metric micrometer, which was nothing like any of the  BSP, NPT sizes which I was expecting. My mechanic suggested I take the connections to Pirtek in Basildon, to see if they could make up a short bypass pipe to screw into the block mountings. They identified the thread as a metric one (M18 x 1.5) and once they'd done that they made up a flexi hose to connect the two unions together. I was concerned that a bit a rubber hose bent 180 degrees might be susceptible to collapsing internally, but they supplied a hose rated to 20 bar, which feels really solid. Also the total height of the by pass is 130mm,, well within the 190mm clearance from the block face where the bypass mounts, to an adjacent bit of chassis leg.
A very elegant solution and for less than £30.
The two guys in the shop were great and said they are often being asked to make up oil and power steering pipes/hoses for old (and not so old) cars which the car makers no longer support. So well worth a visit. Obviously take your old pipes with you. Pirtek have branches all round the country (and the world) and I'm not getting paid commission!!!   

14

Omega General Help / Re: 1999 Omega 2.5 v6 Elite - failed oil cooler

« on: 17 November 2024, 01:50:55 »

I'm going the bypass route.

BTW, someone in the ABS said they are working on a solution for the Omega oil cooler but its not available yet. No suggestion when it may be.

15

Omega General Help / Re: 1999 Omega 2.5 v6 Elite - failed oil cooler

« on: 11 November 2024, 15:06:51 »

Unless someone could definitively say blanking off the two pipe outlets from the block would not affect circulation I was not going to do it. Think I've found a solution if a new or good second hand cooler cannot be found.

The O/D of the oil pipes are 12mm. I can get 12mm x 15mm compression reducers, which I've ordered. Also ordered a 180 degree bent piece of 15mm copper, so I can cut the 12 oil pipes, fit the 12mm end of the reducer over that and then fit the 15mm x 180 degree bend to the other end of the reducers to connect them so I maintain the circulation.  I will have to use a short length of 15mm copper between the reducer and the bend, as the bend is an end feed (soldered) connection, not compression.

But that would work if I cannot get a replacement oil cooler.