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What oil temp would you monitor


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Finally added a few senders to my madman EGT guage today. While the truck is in bits, why not add more stuff :D

I now have oil pressure, I probably didn't want to know, but anyway, it sits around 8-10psi at hot idle (down to 2psi briefly), and something like 25-30 hot at revs, which is a bit poorly. Well it is a bit old. :rolleyes:

Slight pain in that you can't set the low alarm on the madman lower than 15psi, so I've had to turn it off.

So, I have 2 temp senders. One is probably going be tapped into the thermostat housing to give me coolant temp.

So what to do with the oil temp sender? What would be better to monitor, engine oil temp, gearbox or t-box temperature?

For your given choice, where would you tap the sender?

Cheers,

G

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if you do a lot of towing then go for the main gearbox temp, there may be a bolted on casting on the left side you can fit the sender to.

I don't do any towing. Just general driving and some off road. Probably overkill, but I have the sender, so I guess engine temp would give me an idea of how hard the engine is working.

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I don't do any towing. Just general driving and some off road. Probably overkill, but I have the sender, so I guess engine temp would give me an idea of how hard the engine is working.

in that case go for engine oil temp.

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any idea where to tap the sender in to?

I already have the pressure sender at the pressure switch by the oil filter.

look on the forward face of the oil filter head, there's a large blanking plug, remove that & screw the temp sender in, same place as on my 200Tdi.

IIRC you have the link to my photobucket pages showing the temp switch fitted. but if you don't have the link here is the subject temp sender on my engine, looking from the front through the injection pump rear brackets.

post-20-1243191807_thumb.jpg

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I'd be dropping the sump and replacing the big ends and the oil pump pressure relief valve spring.

There's been a stack of people replacing big ends here over the last few years, anywhere from 150-300,000km they are cactus, with the copper backing layer starting to show through.

Some have had the mains worn too.

I'm half way through replacing mine, # 1 big end looks fine, # 2 is pretty stuffed, and I have the same oil pressure you are experiencing.

If you want to see a dodgy bearing, check out this thread here http://www.aulro.com/afvb/technical-chatte...dy-300tdis.html

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I'd be dropping the sump and replacing the big ends and the oil pump pressure relief valve spring.

Hmm, well be that as it may, it'll have to wait as the 110 is my daily driver from today, as the other car now won't start. :blink:

Well, to be honest I don't mind a bit, other than I can't now intentionally break the 110 :D

Have also discovered that the pressure indicated by the madman is, well, mad, depending on the electrical load, so I'll have to sort out a new earth for the sender and see what the pressures are like.

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I'm a bit late on this one, but we (or a previous we as I don't work there any more) used to recommend taking the transfer box temp. The reasons are that you already have the coolant temp of the engine and LT230s run very hot in SA. You want to see what the EP90 looks like after the recommended 40k kms change. Also there is a very handy plug on the side of the box that can be drilled and tapped for the std VDO sensor.

Another reason is that the engines don't fail because of high oil temp - they fail because a coolant pipe bursts. But the gearboxes do fail regularly if the oil level is allowed to drop. This especially applies to LT230s as they tend to leak a bit from the o-rings. R380s don't leak much.

And I am certain you could get a software mod that would change the alarm minimum setting. Just ask, it may be quite simple.

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Hi Jim,

Cheers for the input. I remember you mentioning transfer box temps at the time I ordered the madman. I discounted it because I don't tow, don't live in the alps any more :(, it sure ain't hot here, and generally don't work the truck that hard. But, I'll have a further ponder on that one.

Didn't think (and me a software engineer!) of their being an update or hack for the alarm minimum. I'll get on to madman and see what they say - thanks :)

Am re-running an earth for the sender at the moment (between showers :angry: ), so we'll see what that yeilds....

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Remember all the Madman units are made by one guy in Worcester, Western Cape. This is why they are sometimes in short supply as they are not made in China by a couple of million workers. For this reason he should also be able to somehow modify your unit. It might have to be sent back to SA for reprogramming though.... I don't know enough about EPROMS to say.

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I fuly agree with mr Attrill

Ambient temp in Africa is on the high side. Transfer gearbox temp during night driving on the highway without load is about 67 deg celcius. Still making time to try and see how high it can go offroad

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FWIW I regularly read 65-75*C on the R380 just zipping down the highway at a leisurely 100km/h, and it doesn't have an oil cooler either. (insulated thermocouple on the transfer tube) The t/stat (if fitted) opens at 74*C, or at least the one I have that

I have yet to fit does.

Engine oil temps range from 95-105*C under 'normal' 100km/h highway operating conditions. (insulated thermocouple on the back of the oil filter)

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As a matter of interest, a question for the guys that believe engine oil temp. Will you not be able to pick up rapidly rising engine temp in the exhaust gas temp and the coolant temp?

My Madman EMS gives realtime readings of these two temps. I believe if high operating temp is suddenly reached, it surely must show at least in the EGT?

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I believe if high operating temp is suddenly reached, it surely must show at least in the EGT?

In my head, I'd say not really. The EGT is the temp of compustion. The coolant temp is the temp of the surrounding block. If for some reason, due to a blocked rad for example, the engine starts overheating, the coolant temp would rise, but I don't think that you'd see anything in the EGT, but you'd probably see the oil temp rise.

This is just surmation, happy to be shown otherwise.

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As a matter of interest, a question for the guys that believe engine oil temp. Will you not be able to pick up rapidly rising engine temp in the exhaust gas temp and the coolant temp?

My Madman EMS gives realtime readings of these two temps. I believe if high operating temp is suddenly reached, it surely must show at least in the EGT?

No correlation at all.

EGT's are a function of fuel quantity and injection timing and to a lesser extent inlet air temp. EGT's vary too much and too fast with throttle position, there is no way you'd pick anything else influencing them.

I also believe you can have seriously high oil temps without it necessarily showing in the coolant temp too much.

In the past I've had some serious big end knock hammering over a mountain pass, yet EGT's were kept on the sane side of 720* and coolant temps didn't exceed 103* IIRC. Ambient was around 27-30*.

Engine oil was Delavc 1 (full synthetic) and the engine noise didn't dissipate for around 5km down the other side of the pass, yet coolant temps returned to 'normal' within 200m of the crest.

I didn't have oil pressure or temps monitored in those days.

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Am I right that oil temp affect the viscosity, or the lubrication capacity of the oil.

Will the drop in viscosity not be reflected in the oil pressure? Or is even that not enough to warn the driver?

1001 reasons to use proper oil

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he should also be able to somehow modify your unit. It might have to be sent back to SA for reprogramming though.... I don't know enough about EPROMS to say.

Just to bring this part of the thread up to date, I mailed Brian who makes the madman gauges, and yes, there is an update to allow a lower oil pressure alarm to be set.

All I know so far is that you need to make up a programming cable and have a PC with parallel port, presumably to re-flash the unit. He hasn't send the update yet.

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Am I right that oil temp affect the viscosity, or the lubrication capacity of the oil.

Will the drop in viscosity not be reflected in the oil pressure? Or is even that not enough to warn the driver?

1001 reasons to use proper oil

Engine and gear oils are Newtonian, in that as they get hotter, they get thinner (reduced viscosity) so yes, pressure will drop if the oil gets too thin (hot)

If you monitor oil temps you can plug the numbers into this calculator http://www.geocities.com/CapeCanaveral/3655/VI.html to work out actual viscosities if you have an oil tech data sheet. A T/PDS usually lists 40* and 100*C viscosities and the oils viscosity index (VI).

If you have two of these you can work out the third easily with that calculator too.

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