rdickinson Posted February 19, 2017 Report Share Posted February 19, 2017 The radiator reservoir is leaking at the bottom but only when engine is running. I was told the whole thing needed replacing. Also there is a sensor at the bottom. Can it be tightened up or does it leak thru the sensor? If it's the sensor, why not replace it only?? Seems suspicious to me. Thanks Link to comment Share on other sites More sharing options...
runaway parents Posted February 20, 2017 Report Share Posted February 20, 2017 If the tank is a poly or plastic tank go to ski shop get a ski repair stick lite it and melt it into hole or crack. It will get you buy til you can get a new one. Link to comment Share on other sites More sharing options...
Broncohauler Posted February 20, 2017 Report Share Posted February 20, 2017 New radiator sorry. It leaks only when running because that's when it's under pressure. The fright liners had a problem with the frame twisting and causing the tank to leak. The manufacturer finally came up with a cross brace to solve the problem on our old work trucks. Link to comment Share on other sites More sharing options...
NoDirectionHome Posted February 20, 2017 Report Share Posted February 20, 2017 It leaks only when running because that's when it's under pressure. It (the overflow) should never be under pressure. It's vented to atmosphere. I might guess it leaks when running due to the increase in under hood temperature causing expansion of the plastic. Link to comment Share on other sites More sharing options...
Jack Mayer Posted February 20, 2017 Report Share Posted February 20, 2017 Sorry to tell you this (or to add to it), but it is a "replace". They usually crack at the neck, but they can crack almost anywhere. There is no fix that is worth doing. Take a close look at the overflow tank as well, because now may be the time to do that. Especially look at the nipples on the return. Link to comment Share on other sites More sharing options...
rdickinson Posted February 20, 2017 Author Report Share Posted February 20, 2017 The plastic tank is not under pressure. I lost a filler cap last year and didn't lose fluids. I thought the plastic fitting may have come loose. It's semi visible and thought it could be turned to tighten. It looks like the pipe fitting points down so orienting hose would not be an issue. Truck is going in for door fix so I'll get a second opinion. Is a tank from EBAY going to work? It would not come with a sensor. Price was less than 150$ but from Dealer over 400$ with sensor. I'm wondering if the sensor is or could be an issue? Are they prone to leaking? Where is the overflow tank. My problem is with the plastic tank I top up fluids with. Link to comment Share on other sites More sharing options...
Broncohauler Posted February 20, 2017 Report Share Posted February 20, 2017 Sorry I miss read the original post, I thought you where talking about the lower radiator tank. Link to comment Share on other sites More sharing options...
rdickinson Posted February 20, 2017 Author Report Share Posted February 20, 2017 That's about a 2k fix Link to comment Share on other sites More sharing options...
txdslshop Posted February 20, 2017 Report Share Posted February 20, 2017 Maybe my expansion tank is different. But, it is definitely under pressure when the truck is up to temp on the passenger side of it anyways. It is a pressure cap and is the highest point of the system. With that being said, I would replace the tank and be done with it if it was my truck. Cheap insurance at less than $150 and a little time. Jeremy Link to comment Share on other sites More sharing options...
rdickinson Posted February 20, 2017 Author Report Share Posted February 20, 2017 I lost the fill cap last year and duct taped a big pepper container lit..it worked for a couple of days with no fluid loss. Link to comment Share on other sites More sharing options...
Big5er Posted February 20, 2017 Report Share Posted February 20, 2017 I'm with the pressurized crowd. My Volvo owners manual says : COOLING SYSTEMCoolant Level CheckDO NOT remove the cap to the surge tank whilethe engine and radiator are still hot and underpressure. Scalding fluid and/or steam may beblown out under pressure if the cap is taken offtoo soon. Link to comment Share on other sites More sharing options...
txdslshop Posted February 20, 2017 Report Share Posted February 20, 2017 Yes sir. Same on a regular radiator. You can run the system open and water will not just run out. But, to be able to increase the system pressure and raise the boiling point in the summer... The cap has to be on. Make sense? Link to comment Share on other sites More sharing options...
txdslshop Posted February 20, 2017 Report Share Posted February 20, 2017 Here is a better explanation from Google. I am not nearly as well spoken. LOL While our coolant gives us some wiggle room for running our engine, warmer weather may prove to be an issue. This is where the “pressure” of our cooling system comes into play. When you increase the pressure on a liquid, you raise its boiling point. Our coolant’s boiling temperature of 223° F (106° C) is when it is under 1 psi, which is why most cooling systems are designed to operate at 15 or 18 psi. As the coolant heats up, it begins to expand and create additional pressure. By allowing that pressure to increase, the boiling point of the coolant is increased to around 257° F (125° C) at 15 psi. This gives us better performance from our cooling system as it can absorb additional heat from the engine without boiling. Link to comment Share on other sites More sharing options...
noteven Posted February 20, 2017 Report Share Posted February 20, 2017 oops ...Volvo thread .... Link to comment Share on other sites More sharing options...
NoDirectionHome Posted February 20, 2017 Report Share Posted February 20, 2017 Apparently you are talking about what is called a "header tank" or swirl pot which is different from an overflow tank which is used to keep the circuit bleed during expansion (heating) and contraction (cooling) Link to comment Share on other sites More sharing options...
runaway parents Posted February 20, 2017 Report Share Posted February 20, 2017 Rodger I sent you a pm to explain in more detail what I was referring to. Link to comment Share on other sites More sharing options...
Big5er Posted February 20, 2017 Report Share Posted February 20, 2017 Apparently you are talking about what is called a "header tank" or swirl pot which is different from an overflow tank which is used to keep the circuit bleed during expansion (heating) and contraction (cooling) Stekay, I only have one plastic "tank", of any sort, attached to my radiator. It is also the only filler cap in the system. The internet calls it a "Volvo Truck Expansion Tank Assembly 20519037" Looks kinda like this: Link to comment Share on other sites More sharing options...
Alie&Jim's Carrilite Posted February 20, 2017 Report Share Posted February 20, 2017 Roger, does the tank look like this with the 2 caps? Link to comment Share on other sites More sharing options...
rdickinson Posted February 20, 2017 Author Report Share Posted February 20, 2017 1 cap only, the leak is underneath. A white or yellowed plastic fitting into which I guess a sensor fastens into then a hose nipple below that. Before I start throwing more money down the drain, I want to see where the leak is coming from. Tank by itself is about 150$ on EBAY and over 400$ from a dealer with the sensor included. Or something may be loose, lots of divots out of the road from Victoria to Southern Florida. I-10 thru Louisiana was pretty good and so is Florida. My thermostat rarely goes above 190 f Link to comment Share on other sites More sharing options...
Big5er Posted February 21, 2017 Report Share Posted February 21, 2017 Roger, check here, only $119. http://www.advantagetruckparts.com/volvo-truck-parts/volvo-expansion-tank-20519037/ Says it includes sensor and cap...although it mentions filler and pressure caps $30 bucks is $30 bucks, although eBay might have had free shipping. Link to comment Share on other sites More sharing options...
NoDirectionHome Posted February 21, 2017 Report Share Posted February 21, 2017 It appears there is no method of pressure relief on the Volvo. Is this correct? Link to comment Share on other sites More sharing options...
GeorgiaHybrid Posted February 21, 2017 Report Share Posted February 21, 2017 It appears there is no method of pressure relief on the Volvo. Is this correct? Of course there is, it splits the tanks or makes a sensor on the bottom of a tank leak. Link to comment Share on other sites More sharing options...
NoDirectionHome Posted February 21, 2017 Report Share Posted February 21, 2017 Of course there is, it splits the tanks or makes a sensor on the bottom of a tank leak. That's what I'm thinking... I can't recall ever seeing a design like that. A head gasket leak could be incredibly dangerous if that's the case. Link to comment Share on other sites More sharing options...
Jack Mayer Posted February 21, 2017 Report Share Posted February 21, 2017 Roger - see those two small hoses that enter the top of the tank? Take a careful look at those nipples they attach to with the weird Volvo clamps. Those fittings are often the source of "a problem". Typically the nipple drys out and pieces break off. You can get by for awhile "mcgivering" it....but in the end you will have to replace the tank. Make sure you have no issue there - if you do, then along with the other issue then you should replace the tank. Also, examine the actual radiator closely along the top where the neck is.....you may have hairline cracks there, and an actual leak......look carefully. These are both common problems. And not just in Volvo's. Link to comment Share on other sites More sharing options...
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