jonost24 Posted March 12, 2009 Share Posted March 12, 2009 Had my 90 for about 2 1/2 years now. It's got a 3.5 Efi and 4 sp auto. I've just been having a mooch in the engine bay-as you do, and have noticed there is only one pipe connected to the radiator expansion tank. It goes from the rad, near the filler cap, to the bottom connector of the expansion tank. The top pipe at the neck of the expansion tank is just vented to the open air. There is a second pipe (cut-off and capped) from the radiator. The needle on the temp gauge goes up to about the 2/3 to 3/4 mark. It doesn't appear to overheat or blow any steam from the filler cap. I've attached a couple of photos to help. Should I do anything with these pipes or just leave alone ? Thanks, Jon Quote Link to comment Share on other sites More sharing options...
SacredDog Posted March 12, 2009 Share Posted March 12, 2009 Had my 90 for about 2 1/2 years now. It's got a 3.5 Efi and 4 sp auto. I've just been having a mooch in the engine bay-as you do,and have noticed there is only one pipe connected to the radiator expansion tank. It goes from the rad, near the filler cap, to the bottom connector of the expansion tank. The top pipe at the neck of the expansion tank is just vented to the open air. There is a second pipe (cut-off and capped) from the radiator. The needle on the temp gauge goes up to about the 2/3 to 3/4 mark. It doesn't appear to overheat or blow any steam from the filler cap. I've attached a couple of photos to help. Should I do anything with these pipes or just leave alone ? Thanks, Jon Looks just like what we have on our '88 3.5EFI, it's just a normal expansion tank. It will up when the Water expands and the water siphons back out when it contracts. Looks just right from what I can see in the pics. Colin. Quote Link to comment Share on other sites More sharing options...
Bowie69 Posted March 12, 2009 Share Posted March 12, 2009 The capped pipe looks like an autobox oiler cooler union, rather than a water union, so I wouldn't worry about it. There's probably another at the bottom of the rad. You broke the first rule of LR, if it ain't broke don't fix it Quote Link to comment Share on other sites More sharing options...
scube Posted March 12, 2009 Share Posted March 12, 2009 It looks like the hose you have that is capped off should go back to the radiator or somewhere on the engine/cooling system so there is a circulation path. That’s what happens on my Range Rover. Though the path is different to what you have. I have one pipe which goes to the engine and another that goes to the radiator. Hope this helps Quote Link to comment Share on other sites More sharing options...
ian_s Posted March 12, 2009 Share Posted March 12, 2009 is the v8 original or is it a conversion? Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted March 12, 2009 Share Posted March 12, 2009 Some V8 rads have two pipes, I can't remember what for but I do remember blanking that same thing off on dad's RR when we fitted a 3.9 rad. Your temp gauge could well be lying if the engine is not original - you might need to swap the sender or gauge or both. Quote Link to comment Share on other sites More sharing options...
jonost24 Posted March 12, 2009 Author Share Posted March 12, 2009 The engine and box are from a RRC about an '88 vintage. The conversion was done before I bought it. It used to be a 2.5 NAD. I have the bog brush oil cooler in front of the rad for the auto. I'll leave it as it is, as Bowie69 said "if it aint broke........" I've topped up the rad this morning through the radiator filler cap, there was some coolant it the expansion tank, but only about 1/2" from what I can gauge. Thanks for the replies, Jon Quote Link to comment Share on other sites More sharing options...
acs Posted March 12, 2009 Share Posted March 12, 2009 Had my 90 for about 2 1/2 years now. It's got a 3.5 Efi and 4 sp auto. I've just been having a mooch in the engine bay-as you do,and have noticed there is only one pipe connected to the radiator expansion tank. It goes from the rad, near the filler cap, to the bottom connector of the expansion tank. The top pipe at the neck of the expansion tank is just vented to the open air. There is a second pipe (cut-off and capped) from the radiator. The needle on the temp gauge goes up to about the 2/3 to 3/4 mark. It doesn't appear to overheat or blow any steam from the filler cap. I've attached a couple of photos to help. Should I do anything with these pipes or just leave alone ? Thanks, Jon The lower pipe should connected to another pipe on the inlet mainfold. Centreish on a carbed setup or right hand side I seem to remember on injection. The top one goes to the expansion tank. Quote Link to comment Share on other sites More sharing options...
landmannnn Posted March 12, 2009 Share Posted March 12, 2009 Not sure about the expansion tank. Surely when the water heats up the excess spills into the tank, and when it cools down the water is drawn back. With only a top feed to the expansion tank then water will not be drawn back unless the tank is full, doesn't this type of tank normally have a bottom pipe too? I have seen a whole range of different pipework between the rad/expansion tank/inlet manifold on V8 conversions, it is unusual to see one without a connection to the inlet manifold. Quote Link to comment Share on other sites More sharing options...
jonost24 Posted March 12, 2009 Author Share Posted March 12, 2009 By the way, the heater warms up ok, and puts out nice heat after about 10 mins. Exactly my thoughts landmannnn, surely with the pipe connected only to the top of the expansion tank, the water can't syphon back in when it cools. Do I connect the btm expansion pipe to the capped off pipe at the rad ? I don't know !! or just leave it ? I'll have a look in my RRC Haynes manual see if there are any pics Quote Link to comment Share on other sites More sharing options...
V8 Freak Posted March 12, 2009 Share Posted March 12, 2009 That type of tank doesn't have the bottom pipe.... The blanked off pipe could be the return from the plenum de-icer mechanism. On Efi models a pipe comes form the top of the inlet manifold near pot 1, and into the de-icer on the bottom of the plenum inlet, then returns to the top of the rad. Also serves to remove air from the top of the engine and into the rad. The expansion tank pipe going in at the bottom allows water to expand into the tank and is sucked back when things cool. The pipe is off the bottom in the expansion tank so it needs a few inches of water in order to have some fluid to suck back into the rad. Top it right up. When hot the excess will blow out the overflow tube. It will find it's own level. If it continues to completely empty or go below the level it can be sucked into the rad, you probably have a leak... Neil Quote Link to comment Share on other sites More sharing options...
jonost24 Posted March 12, 2009 Author Share Posted March 12, 2009 Thanks Neil, that's cleared that up, everyones in the know now . Cheers mate, Jon Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted March 12, 2009 Share Posted March 12, 2009 Just to be clear - the expansion tank hose may enter at the top but they usually have a pipe that goes to the bottom to pick up water as the system cools, rather than drawing air back in. Quote Link to comment Share on other sites More sharing options...
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