Using air con rad as oil cooler? - Page 3 - PeachParts Mercedes-Benz Forum

m1tch · #31 09-20-2015, 04:20 PM

Quote:

Originally Posted by leathermang

I suggest that it is not the oil temperature which you need to worry about.. but the top of the aluminum piston which is at risk... as evidenced by the design of the turbo pistons annular oil cooling design.

Would I be able to get a good sense of the internal temperatures of the engine using an EGT gauge?

mannys9130 · #32 09-20-2015, 05:24 PM

The EGT gauge will let you know when you're pushing it too far. In a diesel, running too rich will cause EGTs to skyrocket and melt internals. You have to have air to go with the fuel to keep everything cool. If your EGTs start to reach high levels, you have to let off or you'll melt the head.

leathermang · #33 09-20-2015, 05:56 PM

Quote:

Originally Posted by mannys9130

..... In a diesel, running too rich will cause EGTs to skyrocket and melt internals. You have to have air to go with the fuel to keep everything cool. .....

Yes and to get the most power from a diesel it MUST run fuel lean.

Mxfrank · #34 09-20-2015, 06:54 PM

No. You would know the temperature of your exhaust manifold. This isn't unrelated to piston temperature, but you'll have to check with experienced builders to know how hot EGT can be before the pistons seize. Try asking on superturbodiesel.com

Your bulk oil temperature will be pretty close to your bulk water temperature under most normal driving conditions. When you are pushing the engine hard and the coolant is approaching it's boiling point, the oil will rapidly become much hotter than coolant temperature. This is because water has to overcome latent heat of vaporization before it's temperature can rise further while the oil will be far below it's boiling point. In other words, if your water system is close to it's limit, your oil cooler becomes very important. Other than that, it's just dead weight.

leathermang · #35 09-20-2015, 06:58 PM

" pistons seize ".... or just melt a hole in the top of one or more....

m1tch · #36 09-21-2015, 02:35 AM

Quote:

Originally Posted by mannys9130

The EGT gauge will let you know when you're pushing it too far. In a diesel, running too rich will cause EGTs to skyrocket and melt internals. You have to have air to go with the fuel to keep everything cool. If your EGTs start to reach high levels, you have to let off or you'll melt the head.

Quote:

Originally Posted by leathermang

Yes and to get the most power from a diesel it MUST run fuel lean.

Indeed, diesel tuning seems to be opposite to forced induction petrol engine tuning as with petrol engines running lean on boost increases the temperature and you could get detonation. On diesels, too much fuel on boost increases the temperatures too much. I am currently running the stock pump and I get no smoke on acceleration or idle so I should be ok - would get concerned if the car was at peak boost and blowing black smoke (although kinda okish when off boost until the turbo spools but not ideal).

I agree with the oil cooler being dead weight until the coolant system is maxxed out, a relation used to race a single seater, it used to always overheat after racing for a while as the stock water coolant system was maxxed out. They then simply fitted a larger oil cooler and this then took out enough heat from the engine once the coolant was maxxed to stop it overheating etc.

It's something I will fit but if the oil temp is close to the coolant temperature I should be ok at the moment with the system looped but will still get the oil cooler installed asap.

Hario' · #37 09-21-2015, 08:19 AM

Quote:

Originally Posted by m1tch

My car currently has the oil cooler looped - eg I only have the transmission cooler and not the engine oil cooler, they are thermostatically controlled and I will be running a much larger turbo so need the extra engine cooling.

I do have an aftermarket 19 row oil cooler which I am planning to fit - just looking at other options before I fit it.

Just reinstate the OEM cooer under the OSF wing surely? (because they are dirt cheap).

Edit: You'll need to bin that AC condenser to fit in a proper IC anyway..

Edit-edit: That all looks a bit too clean to me.

greazzer · #38 09-21-2015, 08:50 AM

If you want something maybe a little bigger, grap one from a W116. They look to be around twice the size of the OM617. I didn't measure so I am going off the eyeball evaluation. I meant to grab it before it was turned into toaster ovens but too slow again. I am thinking of putting the W116 oil cooler in mine. The W116 with diesel engine has the same diesel engine, e.g., OM617 but the cooler certainly looks bigger.

m1tch · #39 09-21-2015, 09:33 AM

Quote:

Originally Posted by Hario'

Just reinstate the OEM cooer under the OSF wing surely? (because they are dirt cheap).

Edit: You'll need to bin that AC condenser to fit in a proper IC anyway..

Edit-edit: That all looks a bit too clean to me.

Quote:

Originally Posted by greazzer

If you want something maybe a little bigger, grap one from a W116. They look to be around twice the size of the OM617. I didn't measure so I am going off the eyeball evaluation. I meant to grab it before it was turned into toaster ovens but too slow again. I am thinking of putting the W116 oil cooler in mine. The W116 with diesel engine has the same diesel engine, e.g., OM617 but the cooler certainly looks bigger.

I can't find any OEM coolers to reinstate into the original location, a new one costs around £250 which is why I have got an uprated aftermarket cooler instead which should do the job over and above anything the engine would need.

I am planning to bin the AC unit/system for weight saving and will just get a non AC belt - will probably unplug the lines and air drier when I am under the car next to fit the oil cooler as they just get in the way of everything else under there - not really something needed for the UK! I will be running the stock intercooler for a bit but will uprate that soon - will cost a bit more on insurance for the additional mods but I know I need a better one when I change the turbo.

It looks clean as the engine and car has been looked after over its lifetime, its one of the reasons I got it as it has no rust anywhere and apart from the couple of bodges I have found its in a pretty good condition so a good solid car to start with.