1day

Hi

Looking for ideas as this engine behaviour is starting to annoy me now.

Since renewing the viscous fan (/fan clutch) about 9 - 12 months ago, my engine temps have changed behaviour.

previously, if I hit slow / standing traffic when my oil and water temp's where at normal, the water temp would got to 12 o'clock (up from 11:55) and the oil temp would fall from say 90deg C to 75 deg C (in around over 10 - 15 mins).

Since the fan change, the water temp started to go higher in traffic (12:05) - and oil temps get hotter - even though it's just idling speeds, and can reach 100+deg c whilst standing still.

In the past, I only ever saw 100 deg c was only ever with extended high speeds.

I've chased this for ages now :
- new radiator
- coolant change
- oils (every 3k)
- new water thermostat
- new water pump
- new auxiliary radiator fan switch

The auxiliary radiator fan switch change has definitely improved behaviour (it was broken - the fan wasn't triggering at all). Now that the aux fan is coming on automatically when water temp goes past 11:55, the water temp is staying in normal range (11:55 to 12:00 - maybe 12:05 maximum).

Since then the oil temps are more in control, but, they still rise past what I believe they should be eventually -

example This week, I got stuck in some evening commuter traffic after some fast driving; the oil was already at 90deg c, and the water temp stayed at 12:00 (I could hear the auxillary radiator fan working).

BUT - 20 mins later (still in the traffic jam) the oil was approaching 105 deg c.

I'm wondering if I should change oil brand - I've always used "Silkolene Pro R" - but happy to try something different if it will help.


These problems only happen in standing traffic when the engine oil is already hot. standing traffic with cold oil (under 60 deg c) - and the oil temp will hardly move at all.


Any ideas welcome!

thanks
Jamie

vadas1

Stupid suggestion really ... but are the fan blades correctly aligned?



ralph (vadas1)

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* If it ain't broke fix it till it is *

uk_bm

If the water temp is OK, perhaps the valve to the oil cooler is playing up.

1day

I had that thought as well immediately after the fan clutch was renewed.

I took it back to the local workshop I sued to have that checked, they reported that "yes, they are the right way round"

I will take a photo and post up here for comment / confirmation.


Cheers
Jamie

1day

Also had that thought, and my proper (not so local) M specialist work shop (30 miles away in Dorking) had a replacement oil filter housing (with the valve in the bottom) ready to fit last week...

but

When I arrived at his workshop with water over normal temp, and oil at 95 deg c, Mark (the workshop owner) immediately felt the oil exit pipe, reported that it was "hot" (not simply warm), so therefore the oil is flowing through it.

Conversely the aux fan wasn't running, so, we by passed the aux fan switch and watched the temps fall straight away. however, the standing traffic oil temp problem returned on the way back from the workshop.


I'm starting to wonder if the oil radiator is simply *partly* clogged, hence, not being very effective but still allowing some oil to pass through? has anybody here ever had to clean out / replace their oil radiator?

Jamie

Crash & Burn

Clogged oil cooler good chance to be the culprit. My friend midnight sun had the sae thing. Replaced cooler and temp was back to 80 degrees all the time. My aux fan almost never kicks in and my oil temp is always between 80 and 90, never execeeding the 93 degrees. Even not on hot days AND in traffic.
Anotehr strange thing I do have.
When oiltemp is around 80 degrees. Then start driving fast (ie: 180+ km/h) for about 20 minutes. The oiltemp drops to 70-75 degrees. This HAS to be the oiltemp vavle opening up completetly...right?

Cheers

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E34 M5 Touring, March '95, 100% original, Memory seats, Electric roof, 6-speed, 280.000 km, Fjord Grau.
Renewed: Front suspension and disks, Springs and EDC's, Steeringbox and linkages, Crankshaft bearings, bigend bearings, Ignition coils and guides, clutch, rims (m-paralell) and tyres, All vacuum hoses, Waterpump, thermostat, black powerflex front and rear.
Buildsheet / Touring registry

1day

thanks. after all it's 22 year old radiator, and I don't think the hoses to the oil radiator have been changed yet ether, so, could have gone soft and be loosing shape when hot, again restricting flow.

wonder if you have to take the front bumper off to access the oil radiator?


I think so.

And this also makes me think oil cooler on mine, as, normally my oil temp does the same (drops from hot when starting to go faster), but recently the effect is less than before, ie, low quantity of oil actually being cooled by air. the aux fan only cools water anyway, and that is now working properly.

davidoli

UK-BM is the man !!!!!!!!

Jamie , the oil cooler is attached to the base of your main cooling rad , so ideally , you'll need to lift that out and release the oil cooler / connecting pipework to replace / refresh .

D

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www.classicmdautos.co.uk

uk_bm

When I replaced my aux fan I noticed my cooler was also was caked in 19 years of crud.

Managed to remove much of this in situ by spraying various degreasers through the lower bumper trim, leavin to soak, and using a pump spray filled with soapy water to run out the debris.

You may want to try this first as it could save you some effort. Naturally the area to concentrate on is the centre (aux fan coverage), but an all area clean is beneficial. I'd probably stay away from power washers just in case... Unless you can moderate the pressure.

1day

finally managed to get a decent look at the oil rad today, and yeap, it's covered in 21/5 years of 'yuk' - can't see through most of the fins.

will be cleaning it tomorrow as per your suggestion, luckily I have a selection of low power hand pump bottles :-)