Author Topic: Oil Cooler (Read 10588 times)

rogerh113 · « **on:** June 22, 2006, 17:43:49 »

Hello,

I had an oil cooler on my 230Sl which was disconnected due to my mechanic telling me that it was dangerous due to failure. I have all of the parts needed to reconnect it up, and am seeking a second opinion of the relative value vs risk of the oil cooler.

Any comments appreciated.

Regards -- Roger

113gray · « **Reply #1 on:** June 22, 2006, 18:02:53 »

I would like to hear more on this topic also. Do all 113's have an oil cooler? Where is it? -JP-

DaveB · « **Reply #2 on:** June 22, 2006, 18:10:59 »

Hi Roger, I think an oil cooler would be an advantage if you drive in a hot area. I guess it could all be pressure tested if your mechanic is concerned about it.
The oil coolers weren't originally fitted to 230sl, so the cooler, or your whole motor, must have been retrofitted from a 250 or 280sl or similar. Is the cooler the type that fits beneath the engine support or beside the radiator?

DaveB

rogerh113 · « **Reply #3 on:** June 22, 2006, 19:36:27 »

Hello,

I actually have a 250se engine fitted into my 230sl. The oil cooler is placed on the engine mount, and the mechanic was concerned about oil coolers on general principles rather than there being any particular issue with this one..... it was probably in place and functioning for a year or more before it was pulled. Again not based on failure rather than on concern.

I do notice a slight drop in idle oil pressure (maybe to 27psi) after a longish freeway run on hot days. The idle pressure generally rises rapidly after exiting freeway to the typical 30 to 32 psi range. This is why I am wondering about the oil heat exchanger (probably more appropriate term). Generally there is no noticable issue, but it is also probably not too difficult to reinstall since the exchanger is still in place, and I would just have to install the appropriate oil filter housing and hoses (which I have). I am just interested in figuring out whether I would be coming out ahead or not on the reinstall....

Thanks -- Roger

66andBlue · « **Reply #4 on:** June 22, 2006, 20:35:50 »

quote:
Originally posted by 113gray

I would like to hear more on this topic also. Do all 113's have an oil cooler? Where is it?

Roger and JP,
this previous discussion might be of some use for you:
http://sl113.com/forums/index.php?topic=4940

Alfred
1966 blue 230SL automatic

rogerh113 · « **Reply #5 on:** June 22, 2006, 21:15:22 »

Thanks for the link - I'ld already seen it. It is useful to understand the parts required.

I am looking to understand 'experts' or 'users' experiences and opinions on the value or drawbacks of the oil heat exchanger. I have the parts, I just don't know whether to put them back in or not. Could end up being mostly opinion based on experience - I'ld really like to hear the opinion of folks that have, and have worked on,the heat exchanger.

regards -- Roger

113gray · « **Reply #6 on:** June 23, 2006, 09:39:04 »

OK, Thanks, Alfred. That enlightened me. My '66 230SL Euro does not have the oil cooler & @ nearly 150K miles, apparently has suffered little from its absence. :-) -JP-

Naj ✝︎ · « **Reply #7 on:** June 24, 2006, 13:06:11 »

Hi, Roger,
I'm a fan of the water to oil heat exchanger on the 230/250.
In fact, I retro fitted one to my 230 SL.
In the cold but dry winter we just had in UK, I used the car every weekend.
In the cold, the warm water helps to warm-up the oil and brings it up to optimum temp. faster. In the hot summer, it does its normal job too.[:p]

naj

68 280SL

Benz Dr. · « **Reply #8 on:** June 24, 2006, 13:55:16 »

230SL oil cooler was an option so they could have them from new. I think they're a good idea.

Dan Caron's
SL Barn
benzbarn@ebtech.net
slbarn.mbz.org
1 877 661 6061

rogerh113 · « **Reply #9 on:** June 24, 2006, 14:45:24 »

Does anyone have a drawing or graphic of how the pieces go together (such as routing of the water lines and how the Y junction fits). I know I have all of the parts and hoses, but would like to make sure that I fit them all in properly. Any suggestions on how to clean out the exchanger, which has been sitting collecting debris for the last couple years, would be helpful. Hopefully the oil flow is into the exchanger and then into the oil filter.... I would rather not remove it from the car to clean it out if at all possible.

Thanks and regards -- Roger

jeffc280sl · « **Reply #10 on:** June 24, 2006, 15:42:53 »

Hope this pic helps.

Download Attachment:

cooler.jpg
37.95 KB

Jeff C.
1970 280SL 4-speed

rogerh113 · « **Reply #11 on:** June 24, 2006, 16:47:09 »

Hi,

Thanks for the jpeg, but I think it is a different oil cooler approach. My heat exchanger is on the driver side engine mount, with two pipe connections to the oil cooler and two water lines going to I don't know where - one is to a Y in one of the radiator hoses, the other

That's why I need a diagram....

Thanks anyways -- Roger

jeffc280sl · « **Reply #12 on:** June 24, 2006, 17:12:22 »

Roger,

Sorry about the 280SL pic. Here is all that I have on the 230Sl cooling system. Hope it helps.

Download Attachment:

230sl cooling.jpg
41.45 KB

Jeff C.
1970 280SL 4-speed

rogerh113 · « **Reply #13 on:** June 24, 2006, 19:01:23 »

Hi Jeff,

Thanks for the effort on the jpeg. That covers mostly the coolant reservoir. It appears that one of the coolant sources is from a freeze plug outlet in proximity to the heat exchanger. What I need to know is the other coolant source. There is a tube that is routed around the sump to the passenger side of the car. A 'Y' taps into a coolant source, but it is not as yet obvious how that works. Anyone with a heat exchanger please let me know how the Y is integrated into your coolant system.

Any suggestions on flushing the heat exchanger would be appreciated......

Thanks -- Roger

glennard · « **Reply #14 on:** June 24, 2006, 19:52:09 »

quote:
Originally posted by jeffc280sl

Hope this pic helps.

Roger, More important than the pros and cons of the oil cooler- PART 58 - the rubber seal on the top of the filter. If it is missing , no filtration- worse than hot oil.

Download Attachment: cooler.jpg
37.95 KB

Jeff C.
1970 280SL 4-speed

rogerh113 · « **Reply #15 on:** June 24, 2006, 23:25:51 »

Thanks for the reminder about the seal.

Still looking for info about cooling water connections to the heat exchanger - if you have an exchanger, please let me know how your coolant lines are connected.

Thanks -- Roger

Naj ✝︎ · « **Reply #16 on:** June 25, 2006, 07:17:44 »

Hi, Roger

quote:
There is a tube that is routed around the sump to the passenger side of the car. A 'Y' taps into a coolant source, but it is not as yet obvious how that works

Download Attachment:

DSCN0432.JPG
28.43 KB

The middle leg of the 'Y' connects to the tube going down and round the engine to the bottom (& front)of the heat exchanger.
The rear (upper) outlet on the exchanger connects to the block here. If the pipe adaptor has been removed from the engine, it will have a hex plug (17mm allen key).

Download Attachment:

BurghHse055.JPG
35.03 KB

Hope this helps

naj

rogerh113 · « **Reply #17 on:** June 25, 2006, 08:12:33 »

Thanks Naj, that helps a great deal. It's now pretty clear how all of the connections are made.

Any suggestions on how to clean the oil section of the exchanger while it is in place would be appreciated. I am thinking about opening the drain plug in the bottom and flowing oil into the two topside oil ports - don't think this will get everything out, but hopefully most of it.

Does anyone know if the heat exchanger is pre or post filter. Mercedes engineers seem to be really competent, so I am assuming it is pre filter (output of exchanger gets filtered prior to moving into the block), but I would really like to KNOW. I would hate to do all of the reinstall work and then pump a bunch of muck into the block....

Thanks -- Roger

Naj ✝︎ · « **Reply #18 on:** June 26, 2006, 04:49:52 »

Roger,
I flushed mine with a lot of kerosene but it was off the engine.

I guess the oil goes thru the filter after going thru the exchanger. The oil flow thru the filter is from the outside in and both the exchanger pipes are on the outer periphery of the filter head. Oil from the middle of the filter is pumped straight into the block.
My thinking anyway :|

naj

68 280SL

rogerh113 · « **Reply #19 on:** June 26, 2006, 12:00:25 »

Hi Naj,

I think I'll avoid cleaning the unit with anything that will break down oil - no good way to remove the cleaner....

Given that the oil does enter the block from the center hole in the back of the filter block, your assumption would be correct. Seems logical to put the cooler before the filter, and I do give the Mercedes engineers credit for thinking these things out well.

Time to get a filter body gasket, some hose and proceed. PO seemed to like to use siver paint on his parts, so some cleanup will also be required.

Regards -- Roger

waqas · « **Reply #20 on:** June 04, 2007, 01:24:24 »

I was wondering how this oil cooler re-connection project concluded. Roger, were you satisfied with the results?

Regarding the mechanics initial concerns, how could the oil cooler possibly pose a danger?

Finally, a possibly obvious question (but my curiosity always trumps my trepidation): why does engine oil pressure drop with rising engine temperature?

WAQAS in Austin, Texas

rogerh113 · « **Reply #21 on:** June 04, 2007, 09:51:53 »

Hello,

I ended up not installing the oil cooler. I got everything done except being able to pull the threaded plug in the block for the return water. After applying lots of penetrating oil and the application of a breaker bar, it became apparent that it was not going to budge and I was probably going to damage something in the process.....

The mechanic's concern was that if there is a failure in the heat exchanger the water and oil will mix. I guess if you caught it soon enough (don't know how you would do that) it could be repaired without damage to the engine. Personally I prefer to have as few external lines and connections as possible, so the functionality appealed but there was a downside in all of the connections and lines. Not sure I would put the exchanger in now even if the engine were out of the car (the plug was more accessible).

Regards -- Roger

enochbell · « **Reply #22 on:** June 04, 2007, 10:01:49 »

Waqas,

Hot oil is less viscous, hence causing lower back pressue at the pump. There may also be some effect from hot oil circulating freely in the recesses of the head and therefore allowing for lower volume in the sump, but I don't think that would have nearly (if any) the impact as the effect of lower viscosity from heated oil.

In any case, you should only notice this at idle. At anything above 1200 RPM your needle should be pegged, right?

g

'64 230sl, fully sorted out...ooops, spoke too soon

waqas · « **Reply #23 on:** June 04, 2007, 10:18:04 »

Thanks for the replies!

The oil pressure is indeed pegged at anything above 1200-1400rpm.

Yesterday was a hot day in Austin, and I used the A/C for the first time this season... the engine temp started edging over 200! During idle the oil pressure also dropped to 30~ish, so I got worried. I've never seen it drop before... naturally, some late-night reading through the BBB and this website was in order!

WAQAS in Austin, Texas

al_lieffring · « **Reply #24 on:** June 04, 2007, 10:25:30 »

quote:
Originally posted by waqas

why does engine oil pressure drop with rising engine temperature?

WAQAS in Austin, Texas

The drop in pressure has to do with oil's natural tendency to thicken when cold and thin when hot. The lower the API viscosity the thinner the oil the larger the thicker.

The oil pump pushes oil through passages in the block into holes drilled through the bearings and rotating parts once it has pused through the system it drips down into the oil pan and is circulated again.
So the pressure will vary by the oils thickness, the volume of oil pumped and the clearance of the bearings. or temp, speed, and wear.

I never could explain Multi-viscosity oil to my father he thought oil was either 10wt or 40wt, and there was no way it could get thicker as it warmed up. But realy the multi-vis index shows the oils resistance to change in thickness. So 10w-40 when cold gets no thicker than cold 10wt. and when hot it gets no thinner than hot 40wt. I imagine it's room temp viscosity would be somewhere in between the two.
Synthetics are much more resistant to viscosity change due to thier chemical composition. someone who knows more about polymer doo-dads will have to explain this one.

Al Lieffring
66 230Sl
Jones'n for a new gas tank

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Author Topic: Oil Cooler (Read 10588 times)

113gray

113gray

jeffc280sl

jeffc280sl

glennard

enochbell

al_lieffring