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2.0 TD Thermostats Oil Cooler Heater pipes

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  • 2.0 TD Thermostats Oil Cooler Heater pipes

    Hi Guys - I need some advice on few issues around water cooling, oil cooling and heater stuff.

    So the 2.0 TD engine is a conversion in a 1958 Land Rover so things are not to any normal standard arrangement. I'll break the questions up into different bits to try and make it clear but some are connected.

    Firstly I have been worried that there's a problem with thermostats because the electric fan never kicks in. What I don't know is maybe the engine never gets up to temperature to need the fan, but I've had it stood on fast idle for ages and the temperature gauge is showing high (but I don't know if it's accurate) The fan works as I've bridged the terminals. The fan thermo/switch is mounted in line on the top hose to the radiator and I've taken it out and tested it - it switches at about 86 deg. So then I though maybe the thermostat wasn't opening so I also checked that and again opens at around 86-88 deg, no problem. I did also wonder if there was an air lock as the thermostat does not have the jiggle valve, I've since drilled a little hole in thermostat. I'm bothered that the engine is running hot but I just don't know it, but why does the fan never start - is this normal for these engines, do they run below 88 unless you are really thrashing them? The temperature gauge is an old smiths and seems to work OK but I don't know if it's accurate. I fitted a 10V stabilizer to it but not sure if that is needed or if that would make it read high.

    Second thing is the oil cooler setup. There are two oil pipes feed into a metal tube (cooler) mounted on the water pump and these pipes and the tube get hot. The water coolant pipes which connect either end of this metal tube don't get hot, seems to be no water circulation going through. The left side of the cooler is connected via a hose that tees into the bottom radiator hose. The right side of the cooler connects via a hose to directly under the thermostat housing. Do these hose connection sound right and if so why no coolant circulation through the cooler?

    Third thing is how to connect a heater matrix. I have fitted an old original LR Smiths heater but need to connect into the water system. On the Montego/Maestro setups where/how do you connect up for the heater? I was thinking the best method would be to connect into the oil cooler hose as this is similar size hose but the problem is that one it doesn't circulate as above and if I fit a shut off valve for the heater the oil cooler would also be closed off.

    Hope this makes sense and you can advise.


  • #2
    They do tend to run quite cool, but sounds as though you might have the wrong thermostat fitted, the correct one has a mushroom on the bottom that closes the hole in the bottom of the housing when it opens (same as a Cummins) . The oil cooler sounds as though it is connected correctly, the heater on Montego is connected to the hose between thermostat housing and oil cooler, it is an air blend type, so water is never shut off, you could fit a changeover valva and a bypass to get around this? Only other possibility is that one of the previous owners hasn't changed the coolant every year & head gasket has corroded letting air into the thermostat housing...


    • #3
      Thanks for the reply. The thermostat does have the mushroom plate on the bottom but whether it's dimensionally correct, who knows. I'm going to see if I can get the water circulating around the oil cooler first before I involve the heater. I did get a shut off valve already to cut the circulation to the heater but this was before I realized I'd also cut off the oil cooler if I put it on the same line.

      Just to add a bit of info - when I ran the engine, stationary on fast idle to try and 'overheat' the thing I also had a thermometer sat in the radiator coolant (at the filler cap, there's no expansion tank) and the temp got up to about 75 deg so I would have thought at the thermostat it would have been at least 10 deg higher. I did wonder how the water in the radiator was getting so hot when the thermostat is closed and there's no circulation through the oil cooler - can the heat work backwards up bottom radiator hose? Obviously there was no great flow through the top radiator hose as the thermostat was still closed. What we need is clear transparent coolant hoses so you can see what's going on!

      Also - I have seen that on the water pump housing there is an unused water connection at the top that seems to just pass through. There is a hose connection available on each side but just passes straight through the housing casting - what's it for?


      • #4
        That's the expensive type pump with the engine mounting, you could probably fit the older and cheaper type if you ever need to.


        • #5
          The two top connections are where the top hose goes on cars, elbow from thermostat top, then hose to rad, so you won't need them & as above could use the cheaper single inlet pump. Not sure why radiator is getting hot, but the water route is as follows. Pump pumps water into front of block, then, via restrictor holes in head gasket, to head, then into middle section of thermostat housing. The heater hose is connected to this section and water should always flow through it and the oil cooler, returning to the pump via the bottom hose on the rad. When the engine is cold thermostat is closed and mushroom on bottom of it is clear of the orifice leading to the bottom section of the housing, water can flow down into the bottom section of housing and via short elbow into the second suction pipe on pump, bypassing the radiator completely. When thermostat opens, mushroom closes the bypass and water goes through main bit of thermostat into the top of thermostat housing, through top hose & rad then back to waterpump via the main suction inlet. If you change to the single inlet water pump, you'll need to connect the bottom outlet from thermostat housing to a t piece in the bottom hose. The mushroom bit is quite important, if it doesn't block the orifice when thermostat is open, then pump tends to suck water away from heater (and it won't bother going around radiator if there is an easier route)...missing the thermostat out can be very fatal very quickly, unless you block the bypass hole up! If you can get hold of a small electric water pump it might be an interesting experiment to fit it in the heater/oil cooler line & see what effect it has, I fitted one to a car once, as the expensive water pump packed in & I didn't fancy buying a new one...on the car it is part of the engine mount, so cheaper option isn't available! good luck!


          • #6
            Thanks again for the info the description of the water route was very useful. I decided to pipe up the heater matrix on the oil cooler line because I need to check the heater doesn't leak etc. Obviously at this stage I will keep this line through flowing and add a valve and bypass in the future. I filled the heater and hoses with a hose pipe before making the final connections so I knew it wasn't air locked. The coolant is now flowing through the oil cooler and heater part of the system but the thermostat and the fan switch still don't seem to kick in. I got the engine up to temperature on a run and then left it running stationary for over half and hour. It just seems to be that the engine just does not get to the temperature to open the thermostat and therefore the fan switch never sees the hotter coolant to trigger the fan. The whole radiator is getting hot though which is strange without the high flow from the open thermostat.


            • #7
              Hard to see how the radiator is getting hot, but doesn't sound as though anything too horrible is going on, if water is flowing through heater/oil cooler circuit then pump must be working. I've sometimes used this sort of thing to try and trace coolant flow, not super accurate, but gives a clue as to how hot (or not!) things are getting..


              • #8
                Sorry to bring this post back to life but I’m still not convinced that the coolant circulation is right on my engine.

                After cylinder head rebuild I did have problems getting the coolant to go round the heater but that seems ok now. So simple questions are how do you know that the water pump is working or efficiently other than the engine rapidly overheats?

                I took the radiator cap off and ran the engine up to temperature but don’t seem to see movement in the water through the radiator, is it obvious when the water is circulating? I’m assuming the thermostat is opening. I fitted new thermostat after previous posts.



                • #9
                  On the cars it is difficult to see if the coolant is circulating (no rad cap on radiator), but on a Land Rover you should be able to see it flowing out of the top hose into the top of the radiator. If you clamp the heater hoses either side of the oil cooler & disconnect the one coming from the heater, then fit another hose to it, aim the open end of this hose into the filler hole then start the engine you should be able to see if it is pumping through the heater circuit?


                  • #10
                    Good idea!
                    So I tried this today and yes the water does circulate around the heater hose so the pump is doing something. I expected it to be going full bore through that small heat hose though, even when I clamped off the bypass hose it was still very light flow, but of course engine only on low revs.

                    Maybe I’m just getting paranoid about the cooling but it just doesn’t seem to do what you would expect.


                    • #11
                      Odd, you'd expect quite a lot to be coming out. Mind you, I got paranoid about mine & put an electric water pump in the heater return hose & it made no difference at all as far as I could tell! Taking the pump off to check for wear involves quite a bit of dismantling...A cheap electric pump from ebay might be worth trying, if the existing pump is worn it should make a difference...