Oil Temps

Took my Valve Covers off a few days ago to check for Emulsification of the Oil.
It’s one of the possible causes of the infamous Cam/Tappet failures on the CARC models.
Cold, damp Climate, shorter journeys = moisture in the Oil.

It’ll usually show up on the front of the Covers, sure enough there was some on mine.

Owners with Sump Temp Gauges (Dipstick type) report fairly low Oil temps (<100°C), even in hotter Climates than ours.

I’ve fitted a temp Gauge to mine, Thermocouple type, sensor in the large Banjo Bolt on the right of the Block, Cooler feed line.

(Blanking Bolt fitted here).

Gauge readout mounted to H/Bar Clamp.

I had the lower half of the Cooler blanked off prior to finding the ‘Mayonnaise’ in the Covers, will be blanking it off fully now for the rest of Winter, will adjust as necessary subject to temp readings.

Only if it’s 4 valves per cylinder, as far as I know. And even then not certain. Besides which cams would have a continuous oil feed.

This particular theory is Mike (as I understand it), that the moisture in the Oil causes very slight corrosion on the Cam lobes (when the Engine’s sitting idle), which leads to premature wear of the surface.

Don’t believe it.

Well if true it must follow there’s lots of other steel bits in there going rusty.

Edit: of course if you want to stop the mayo balance short journeys with an occasional long one to boil the water out.

My Triumph T140’s primary drives uses to look like they’ve got yoghurt in it in the Winter after commuting into town 5 days Mon - Fri, had to change the oil every Saturday.

Thanks for the update and pics, Doc. I’m always watching if you get any unusual data :nerd:

I only use my bike for long runs have never had problem with emulsification and have 2 sets of flat tappets fail. the problem is one which a number of car manufactures are also having with this design of cam arrangement, zinc has been removed from oil because it destroys catalytic converters but is good at preventing metal to metal contact in high load areas such as cam lobes. Honda had a similar problem on the first generation VF engines in the early 80’s and recommend that on every oil change you added a Honda additive which I think was ZDDP

Yes I’ve mentioned it before, you can get bottles of ZDDP additive. Got mine from Frost Restorations I think.

There are ‘classic’ and diesel oils which include the additive as before, but don’t think you can use those in a more modern CARC model? Has to be part or fully synthetic?

I wouldn’t be surprised Mike, but the Cams and Tappets are exposed more than other critical parts (Big/Small ends for example), and another theory is that they’re too small (surface area-wise) for the loading on them.

. . . if you want to stop the mayo balance short journeys with an occasional long one to boil the water out . . .

That’s just the problem though Mike, the Oil Temp tops-out at around 90°C no matter how far you go, even in hotter and drier Climates than ours.
Any Thermostat-less Cooling system that can cope with hot Climates will over-cool in our Winter.

As to the Oil specs, you can get Fully Synthetic Oils with high ZDDP content.
Morris do one, and I’ve heard from more than one source that Engines using it don’t suffer Cam/Tappet failures.

I’m using Penrite 10 tenths Racing Oil myself.
ZDDP content exceeds 2200ppm, twice that of Mobil 1 for example.

Fitted new Gauge on Monday, original display failed after one day!
Was only a cheap Chinese thing so not too surprised, would probably have been OK in a car.

New one . . .

From here . . .
4+ yr Battery life.

On a 45-min Ride-around locally, 50mph tops, bit of stop-start Traffic.
Hit a high of 112°C while Riding, 117° sitting at Lights/Junctions.
Rocker Covers too hot to hold Hand on for more than a couple of seconds.
Cooler is fully covered at the moment, will tweak that if Temps rise to the high 120s or thereabouts.

Riding into work last night, mostly Motorway, 80mph average, 7°C Air Temp,
Oil temp sat at 108°C or thereabouts, rising as before to around 117° when sitting at Lights/Junctions.
Sender is still in the Cooler feed-line Banjo Bolt. Might move it to the Sump Plug at the next service.

Ride home this morning, same mix of Urban-Motorway-Urban, 7°C still, but raining fairly steadily.
Never got above 85° on the M/way doing 85-90mph (0440, so nice and quiet!), crept up to 95° the three miles through Town from M/way to Home, then went up to 105° sitting idling for two mins once I got home.

Once we hit Winter proper here, I might look at more insulation on the Cooler, or maybe some on the Sump as well, depending on what the Gauge shows.

Whether cool Oil is the cause of Tappet/Cam failure, just part of it, or nothing at all to do with it, I’m happier with my Oil at these Temps.

If you’re worried about the tappets then add a bit of ZDDP additive.

OK then!

Again, don’t know if that actually has anything to do with the Cam/tappet issues, but I don’t think it can hurt.

Checked my Tappet Clearances today. Left inner Ex was a ‘smidge’ tight, as were both R/H Inlets, rest were spot-on (0.004 In ~ 0.006 Ex).
More ‘mayo’ in the Rocker Covers, more than when I was running with the lower Oil temps.
I’m thinking that the higher temps (100+°C) are boiling-off the moisture nicely now, but the vapour’s got nowhere to go once it reaches the Covers.
I’ll be adding some breather outlets to them to hopefully remedy this.

None in the left Head itself though, and just a few minor traces in the right one.

ZDDP superb additive for the engine; unfortunately not user friendly for the Catalytic converter. It`s how to get the balance right.

Although I have no scientific evidence other than what I’ve read of the experiments here and by other Stelvio owners, it would seem that for our climate, these engines are over-cooled.

I have ridden my bike is 30+C here in the UK (yes, really :slight_smile: ) and similar temps over in Spain. Although the engine was “proper 'ot, guv’nor”, it still ran like clockwork in traffic, although I sensed somehow that it didn’t like it. Over on ADVRIDER.COM, plenty of our cousins over the pond ride in Nevada-desert-like temperatures with hardly a grumble too.

Taking into account there must be an efficent heat zone that works best, is there a case for covering the oil cooler with foil during the colder, wetter months? I don’t use mine for short journeys but even after a good long run (50+ miles) in winter, the engine never seems that hot. An oil temperature guage would be a useful addition to prove/disprove this however I can imagine my paranoia levels increasing with the entertainmant that would bring!


Yes I agree, and why liquid cooling is superior.

I’ve pretty much covered it here (and on ADVRider/GuzziTech).
From my findings with the Temp Gauge, the Engine is definitely over-cooled in the UK.
As you point out, owners in much hotter Climes (35+°C) have no issues with overheating.

It’s not really on to design an Engine without some form of Thermostatic control in the Cooling system in this day-and-age.

My Cooler is completely covered at the moment, and the Oil Temps are around 105-115°C most of the time now (once warmed up 20-25mins).
Optimum Oil Temp is around 120°C I believe, so I’m happy with it as it is now.

I also think the Breather system’s capacity isn’t adequate for the size of the Engine, and it should really have the outlets at the top of the Covers, not at the back of the Head as designed.
Look at just about any other Engine, the Breather outlet is on the very top of the Valve Cover.

Thanks for the info, Doc.

I tried blocking the airflow through the cooler today, using aluminium foil. I just did about 60 miles with the ambient temp’ between 11C and 14C. No problems at all but on the other hand I can’t say that the engine was any hotter at the end of my journey than it would have been with airflow through the cooler (it’s a regular journey so I can compare like with like).

Perhaps it would make a difference on shorter journeys, which I rarely do.


I didn’t notice/feel any real difference in Engine temp either to be honest, but I’ve read that a lot of the Cooling takes place from the Sump, so maybe you wouldn’t notice that 10-15° difference anyway.

I’ve ordered another Sensor now, I’ll be fitting it to the Sump so I can compare temps between the two positions.
I can’t see there being much in it myself, but someone on another forum thinks there may be.

We’ll see . . .