CAS oil leak - and oil cooler hose.....

[PJR-Elan]

Hi all,

I am using 10w60 Shell and my oil level seems to drop noticeably on the dipstick on a weekly basis. The car doesn’t smoke, and the head was off recently for a precautionary head gasket and all looked really good.

I did spot that the CAS o ring was leaking and I have just replaced that. My question is, how much can the CAS leak? Would it show on the dipstick over the course of a week?

Crazy question, I know!

[Rambo]

10W 60 oil - that's quite a high viscosity. Have you always used that grade ?

Aside from that, I don't think the odd few drops leak from a CAS o ring would show up at all on the dipstick (difference between max and min is ~1L)

Did you have a sniffer test and compression test carried out prior to replacing the HG ?

[HJ2]

If you pull the inlet hose from the turbo, does it spin freely and unobstructed?
A faulty turbo would consume some oil, but it would be visible in the rear view mirror if you floor your m100!

[PJR-Elan]

Thanks - some answers to your questions.

The oil grade was what was recommended to me - I’ve not owned the car long - and it seems quite popular on here. With modern synthetics, these grades are now available, and it sounded like a good range of protection.

The turbo is as new, having just been fully remanufactured by CR Turbos, and there is no smoke or any other issues with that. The head gasket was done very recently and everything was exactly how it should be. No signs of burning oil, etc. There was a sniff test before the HG was changed which came back fine, but I decided to do the HG anyway whilst the cam belt was being done.

I’m not completely sure that I am losing lots of oil: the oil is clean and fresh and getting steady and repeatable dipstick readings is not easy. When I replaced the HES last week I noticed that the CAS had been leaking and also saw oil where the head/block joins. To answer my own question, I need to collect more data to see if I am losing much oil, but I was just curious as to whether anyone has experienced noticeable oil use as a result of the CAS leak.

[Rambo]

I only had a small weep from my (upper ?) o ring. And I hadn't even spotted that until Dapinky did when we were comparing my CAS with Kathryn's CAS at Castle Combe 2 years ago (we were in the process of changing Kathryn's HES)

Dave very kindly changed the one that was passing fluid. He had spare o rings in his car plus the necessary tools

The leak was so small that it would never ever have registered on the dipstick

[GeoffSmith]

Check the O ring on the rear cam blanking plug. It is the same as the CAS O ring (A100E6562S) and also leaks.

[Rambo]

Re. your oil leakage I would top up the oil to the max mark and note the mileage. Every week check the dipstick vs mileage and note any change etc... Also if the car is garaged park it over some newspaper and see if you have any leakage

[Rambo]

Check the O ring on the rear cam blanking plug. It is the same as the CAS O ring (A100E6562S) and also leaks.

That's the one Dave didn't do on mine as it was OK . Although I think the main reason was that we were running out of time as it was beer o clock

[PJR-Elan]

Thanks guys.

The blanking plug seems dry so I didn’t disturb it even though I bought an o ring for it. The CAS o ring was hard and flat - barely protruded out of its groove. I think it’s possible that it could have allowed almost a constant (albeit minimal) flow of oil.

I found this quote in the oil viscosity thread:

“Occasionally, touring engines will use oil for no apparent reason. This is often due to the oil level rising in the crankcase due to air retention, leading to oil loss through the breather. The answer is to move to a lighter grade of oil to improve air release.”

I did feel slightly uneasy going for such a thick oil, but the oil recommendations on here and on the automatic systems suggested 10w60. I have just topped it up with shell 10w40 synthetic.

I don’t think the car is dropping oil but it’s outside on the drive (and it’s been very wet) so I can’t exclude that possibility.

I shall monitor and report back.

[Rambo]

Hi - if its wet you will easily see oil drips under the car

I have used Petronas 5W 40 fully synthetic oil for many, many years now without any problems. This was on the advice of an expert and automotive engineer who also raced performance cars

[GeoffSmith]

Check the O ring on the rear cam blanking plug. It is the same as the CAS O ring (A100E6562S) and also leaks.

That's the one Dave didn't do on mine as it was OK . Although I think the main reason was that we were running out of time as it was beer o clock

Oh, that's right. I remember it well:
"Well that's curly's CAS O ring sorted but it's pissing oil out the back one if you get your hands dirty and look carefully."
"Should we do it?"
"Pub's open."
"There you go Mark, all sorted. Let's get to the pub. Drinks are on you"

[Simon_P]

Please check your oil cooler hoses before starting your engine again - particularly the inner one which is prone to pop off.

I stick with oil in the original recommended viscosity range as I know that's where the testing was done. Lotus did recommend 60 oil but I wonder how much testing they did, or if it was just to standardise?

10w 60 is comparitavely thick when cold and thick when hot.

[dapinky]

Please check your oil cooler hoses before starting your engine again - particularly the inner one which is prone to pop off.

I stick with oil in the original recommended viscosity range as I know that's where the testing was done. Lotus did recommend 60 oil but I wonder how much testing they did, or if it was just to standardise?

10w 60 is comparitavely thick when cold and thick when hot.

Especially if you have gone to the 60 weight oil recently - the increase in oil pressure will put added strain on those 2 pipes which wasn't there before.

I use the 10W-60 (Fuchs) as my engine is approaching 140K miles..... but only went to the thicker stuff once it was past 110K.... it seems to like it, and keeps a more consistant pressure.

[Rambo]

Good points made by both Simon and Dave. If your old oil cooler hoses let go you will know about oil loss. If you have gone to the trouble of having your turbo reconditioned and the head gasket done it might make sense to replace the cooler hoses or the joints. Pirtek (nationwide locations) are a good source for that.

I use the 10W-60 (Fuchs) as my engine is approaching 140K miles..... but only went to the thicker stuff once it was past 110K.... it seems to like it, and keeps a more consistant pressure.

PS If your engine ever goes bang at least you can say it's been well Fuched Dave

[dapinky]

PS If your engine ever goes bang at least you can say it's been well Fuched Dave

Hopefully no banging in the engine..... It won't be started up again until after the cambelt etc is done next week (plus whatever else gets looked at/changed due to the inevitable project creep.

[Rambo]

Some useful info here...viewtopic.php?f=122&t=25516

[PJR-Elan]

I’ve just dashed out into the wind, rain and darkness to inspect the upper oil pipes and the lower one that is visible from above.

Starting with the bottom joint, that was clean and dry. There are no drips from under the oil cooler.

The upper joints screw fittings look good. I felt the joint inside the wing and the pipe crimping does not seem to be of the original type.it had a slight hex feel to it and no flare in or out. Those joints felt dry - as far as you can tell on a windy damp evening.

However, the upper pipe of the two is fitted so the metal pipe has its outer curve as a low point. Touching that, there was a drop of oil on it. Looking down at the top of the chassis member directly below it, it looks like there has been a drip or two.

I did recently drain and refill the PAS (and the pas hose below the reservoir has a weep!) so I cannot exclude the possibility that this is from a spillage - I spilled a couple of drops but dried around the PAS reservoir and I’ve probably driven 20 miles since then and I would have thought any drip would have dried on the hot pipe or been blown away. But I know that oil can cling on sometimes for ages.

Assuming the oil pipe is weeping, I guess the chassis below is funnelling any drips down to the ground in an area with lots of road spray and air flow, and therefore I shouldn’t be surprised that I’m not seeing any telltales.

Is t he oil radiator of a thermostat? If not, I think I may dry the pipes throughly and do a loop around the village and see if they develop a drip on them.

I think the next step is to take out the wheel arch liner, clean up all the pipes so they are squeaky clean and then test drive the car to see if they remain so.

Thanks for the input all.

[PJR-Elan]

Having just found a picture of the SJS alternative, I think these are what I have fitted. If they are weeping, are they equally prone to suddenly letting go?

[PJR-Elan]

So, I wiped off the wheel arch liner today and found two very clean and lovely oil cooler pipes. I cleaned them forensically and then ran the engine. The upper pipe was dripping from the union between the fixing and a later Pirtek hose.

The other was perfect, and the hoses themselves look pretty new.

I’ve had a local independent hydraulic guy recommended to me so the pipe will go there Monday morning.

Good call from you guys who suggested this might have been the source of my oil loss. It looks like it was dripping when hot. This went onto the top of the chassis rail and no doubt rain, mud etc stopped any oil ever making it onto the drive.

[PJR-Elan]

I’ve now taken the hose to ATH Hydraulics in Stonehouse Gloucestershire, having had them recommended to me. I did consider Pirtek, but the failed pipe has a Pirtek hose on it so I’m guessing they might have made it and so I thought I’d try someone new.

I’ve not had it back yet, but the chap was considering brazing a cut-down part of a more substantial fitting to the original metal swan neck so as to make a more reliable seal. He sounded very thoughtful and knowledgeable so I have my fingers crossed.