Oil Cooler Notes [more accurately:  Coolant/Oil Heat-exchanger!]

First Published Oct 2021, R. Kwas  [Comments Added]



Reference Information
    Oil Cooler Delete Kit
    Oil Temp Gauge not working?


Exploded Assembly Diagram of the original Oil/Coolant Heat exchanger type Oil Cooler, and associated. 
The colors of flow are relative and shown here for when engine is fully warmed and at thermal equilibrium...
Coolant temp
is cooler than Oil Temp, so oil sheds heat into Coolant and returns to engine cooler...see text!

The Original Equipment Oil Cooler fitted to early 1800 vehicles (also known as a plate mine or Tellermine in German from the clear resemblance!), was more accurately a Cooling System to Oil, heat-exchanger, because being plumbed into the Cooling System it was supplied with the warming Coolant during warm-up after a cold-start, when the oil temp actually lags well behind the Coolant temp, it would therefore serve to warm the oil faster than if it was simply allowed to warm on its own.  This warming of the oil actually served to more evenly warm the entire engine, which from a thermal viewpoint, is not such a bad thing!! 

However, nothing is forever...especially those assemblies subjected to great temperature stresses...like the OE Oil Cooler!...and these are unfortunately known for failing!  Were these produced for Volvo by Lucas...just wondering...! 

If an oil cooling function is truly necessary and desired for hard engine service, a more common Oil to Air heat-exchanger is recommended. Besides being more effective than the OE Cooling System to Oil, heat-exchanger (because of the low temp difference between the two systems in the first place), an Oil to Air Oil Cooler would also never have the risk of leakage between the two systems...at the very worst, it a leak were to occur with such a cooler, this would of course not be good, but it would be in to the open, where it would hopefully be noticed...at least it wouldn't result in the oil in the Cooling System as seen following.


OE Oil Cooler Failure:

From a posting complaining about significant amount of Oil in the Coolant Expansion Bottle after a Cyl Head Gasket change: 

This ain't right, and unfortunately, not so rare!  Symptom of OE Oil Cooler Failure!
Malcolm Reed picture from 2020.  Permission to repost requested.

My response: 

"More than a few drops of oil in the Cooling System after Head Gasket change is BAD and indication something is very wrong. The FIRST thing you need to answer is IF you still have the original factory stock Oil/Coolant Heat Exchanger (also commonly known as an Oil Cooler), installed...you may have a leak between the two systems, and since Oil is always at a higher pressure, it will leak into Cooling System.  Again IF you still have that original "Oil Cooler" (and these are known for failing in this manner!!!)

I suggest removing it ASAP and having it pressure tested, for leaks between the two systems, which would confirm it as the source of oil in the Cooling Sys, and would mean you have found and solved the problem without further opening up the motor!

This "Oil Cooler" was installed in early P1800 as oils of the day would/[might under certain conditions of hard use], operate close to their temp limit**,  so Volvo felt a cooler should be installed for reliability reasons (and we know this is not an issue thankfully!).  Modern oils have a higher temp operating range so Volvo engines in normal duty do not need oil coolers...and they sure as hell don't need a cooler which allows it to leak into Cooling system! If you have it, loose that "Oil Cooler"!!" 

**  [It is also typical that the Oil Temp Gauge rarely comes off the cold peg for most owners, who are not operating on the Autobahn, such that complaints of a non-"working" (actually non-indicating!) Oil Temp Gauge are not uncommon!...so one has to wonder under what operating conditions the oil actually got to its upper temp limit...maybe rallyeing at the Mediterranean in scorching high-summer, but this demonstrates just how ultra-conservatively and with how much operating margin Volvo designed and produced their engines, and sent them into service!!],


Permanent Removal of the Original Equipment Oil Cooler [Coolant/Oil Heat Exchanger]: 

This procedure has been prepared with the utmost care. However, it is strictly a guide to be used in conjunction with normal, cautious shop practice.  I cannot accept liability for all your actions.  Work Safely! 

Before starting this process, it is recommended to have the Items 1-3 at hand (source of Volvo PNs:  GCP.se parts catalogs). 

Refer to Exploded Assembly Diagram above.  

Cooling System should be drained before proceeding.  There is also a Draincock on the bottom of OC to allow draining.

Remove Lower Radiator hose. It should be replaced with one, which does not have the additional return hose provision.  (Item 1, PN 273191-7 or 271194-1)

Remove the upper formed pipe connection between OC and Cylinder Head, and associated Seals, and seal the opening in Cyl Head with a Seal Flange.  (Item 2, PN 418213-5)

Remove Oil Filter, then the Nut and Washer which secures OC to central Threaded Nipple, then the OC and associated Sealing Ring. 

Since the Oil Cooler is installed in a design stacked with the Oil Filter, the pipe threaded into the engine is too long to simply allow removal of the Cooler, and refitting the Oil Filter.  When permanently removing the Cooler, this pipe must also be replaced with the standard short pipe which was installed when no Cooler was fitted.  (Item 3, PN 418440-4)  

Refill Cooling System in the normal manner, and check oil level at Dipstick.


Optional Step:  List the removed OC on an on-line auction site, and get prime dollar for it for some poor schmuck, and let him install it so that it can fail for him...which it will! 

Typical auction listing for a used Volvo Oil Cooler.  ["Gently used, but sold as-is!"]
Shown up-side-down, because the listing guy really "knows his stuff"...



Volvoniacs Thread:  Ölkühler "Tellermine":  http://www.networksvolvoniacs.org/index.php/Spezial:AWCforum/st/id6305

Ever wonder what the Oil Cooler looks like inside?  This Norwegian 1800 owner has done some very nice work, including a full documentation, of refurbishing an OE Oil to Coolant heat exchanger, on his blog.     https://p1800s64.blogspot.com/2020/12/oljekjler-b18b.html  He did mention that his was also leaking before the procedure...!

Sigfred Søvik picture posted with his kind permission.


Reference Information:  

An Oil Cooler Delete Kit is available:


Oil Temp Gauge not working?  Are you sure?

This applies equally to the early carbureted, as well as late, injected 1800s...for example, Gauges of an 1800E are shown here: 


Brian Hart picture at 100mph, on a "track day"...used with his kind permission!

The Oil Temp is barely tickling off the cold peg...and that at 100mph!
...and it looks like Brian has a 70ºC Thermostat fitted.  See also:  Temperature Gauges 1800E/ES Notes


Explanation:  The Oil Temp Gauge is calibrated quite low, that if it were used to measure Dr. Evil's "...liquid hot MAGMA", or some obscenely hot sauce, where Scoville units are measured in scientific notation because there are so many zeros... (to each their own, but why anyone would do that to themselves is completely beyond me! Reference:  https://en.wikipedia.org/wiki/Scoville_scale ), it would only register somewhere in the middle of the scale...!

Reference Information:  



...saw no-one...with a properly functioning sensor and gauge...dare I say:  Ever!  This is more a symptom of a non-cycling V-Stabilizer!  See:  Symptoms of non-cycling V-Stab


External material sources are attributed.  Otherwise, this article is Copyright © 2021-2022.  Ronald Kwas.  The term Volvo and names of other companies appears here for reference only.  I have no affiliation with any of these companies other than to keep their products working for me, help other enthusiasts do the same, and also present my highly opinionated results of the use of their products here.  The information presented comes from my own experience and carefully considered opinion and gathered reference data, and can be used (or not!), or ridiculed and laughed at, or worshipped, at the readers discretion.  As with any recipe, your results may vary, and you are, and will always be, in charge of your own knuckles, and future! 

You are welcome to use the information here in good health, and for your own non-commercial purposes, but if you reprint or otherwise republish this article, you must give credit to the author or link back to the SwEm site as the source.  If you don’t, you’re just a lazy, scum sucking plagiarist, and the Boston Globe wants you!  As always, if you can supply corrections, or additional objective information or experience, I will always consider it, and consider working it into the next revision of this article...along with likely the unique metaphor and probably (likely) wise-a** comment. 


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