1985 Mondial QV Cabriolet Hi everyone. Is it possible for the cooling system to be sucking in air somehow and displacing coolant out of the overflow hose? If there was some sort of area leaking my assumption would be coolant would be coming out of that area since the system is pressurized instead of air getting into the system. What has been happening for me is coolant continues to be coming out of the coolant over flow hose. It is difficult to determine the consistency of it but I notice on some drives after parking it there will be a puddle and sometimes a friend notices while driving behind me. It doesn't necessarily happen every drive. The reservoir in the rear seems to be staying a pretty consistently half full. The amount of coolant coming out of the over flow hose has seem to be decreasing. This has been over a time period of months and numerous drives. I have tried opening the bleeder at the radiator on multiple occasions, have tried using a vacuum/pressurized tool, etc. Other than the issue as described above, the car runs excellent, has proper power, and runs at a good temperature. Suggestions on next steps?
The only place it could be pulling air in, is via the water pump seals, as the rest of the system is on the pressure side.The impeller and discharge casing is on the pressure side
A. Have you pressure tested the cap? B. If you leave it alone, do not add water will the system get low and eventually start running hot? C. When and how did it start? A common issue is someone will see the system burp out some coolant so they top it up, It burps out more, gets topped up. That can continue forever and is not an indication anything is wrong. It needs airspace to function and is better at establishing how much air space is needed than we are. Something could be wrong but you could just be over filling it.
I dont know the level of fluid in a cabrio, but in a coupé its 16 cm under the opening of the pressure cap....so maybe to much water in your tank ?
Is that for a 2 valve, 4 valve, 3.2 or a t? They are different. Also what is your ambient temp? You make 16cm sound definitive. It is anything but.
Its for the mondial 8 and QV Coupé ... WSM = Image Unavailable, Please Login Image Unavailable, Please Login I have no WSM for Cabrio.... And in reality, my QV always stays at 16 cm....if I put more water in the tank, it gets spit out !
I have a 3.2. The manual lists the fill depth as 2.3" / 6cm below the "filler plug base". The drawing is much less clear and doesn't really define what the base is, although I use the lip at the base of the plug. It is a more horizontal tank. As a note, there is also a bleeder at the water pump. It does not come with a bleed screw that can just be loosened, although someone here at least used to sell them. I don't have a good solution, although they certainly will burp a bit when overfilled.
"And in reality, my QV always stays at 16 cm....if I put more water in the tank, it gets spit out !" of course with a cold engine ! 16 cm from top of filler opening....and like Brian mentioned, depends on ambient temperature, full moon, my wives .....
Thanks everyone for the replies and insight. Here is some additional info and questions related to the replies: 1. Location: I'm in south eastern Wisconsin and am driving in temperatures from 45 degrees F to 90 degrees F. 2. It has always spat a little coolant out the overflow hose since I have owned it (a couple years). I had not driven it BEFORE doing a belt service so I cannot say if this issue existed prior to me. I did a belt service thus had to remove the metal coolant pipe and refill the coolant system. For the 2022 driving season all I did was open the radiator bleeder a few times that whole driving season, the temperature never went very hot, minimal coolant spat out of the overflow hose. It seemed no matter when I opened the radiator bleeder valve some air would come out then eventually just coolant. 3. Early in the 2023 driving season the temperature on one of my first drives DID get hot. I stopped the car, let it cool down, drove it home, put a laser thermometer on the radiator and the very top of the radiator was significantly cooler than the rest of the radiator suggesting there was a bubble. I opened the radiator bleeder and the air pocket dissipated. The temperature was proper after that. 4. Later in 2023 I hooked up a vacuum/pressurized system to fill the coolant system as I assumed there was an air bubble somewhere in the system I was not getting out. This seemed to work well, I heard fluid/bubbles moving at the radiator, the system took in coolant, etc. I had topped up the coolant reservoir so it definitely had too much coolant in it at that point. Essentially the next drive the overflow poured out coolant that was probably equivalent to a quart while the car was driving (a friend noticed it and stopped me). It had done this one or two more times after this as well. 5. It has continued to push coolant out of the overflow hose and lately it is less. I do not know if it is occurring while the car is running but it definitely leaves a small puddle AFTER the car has stopped and turned off. Also, the heater is now NOT working as of yesterday. It had worked every time prior. It is not running a hot temp. It stays below 100 degrees C but we are now in cooler weather in Wisconsin (yesterday's drive was 45 degrees and 60 degrees F). 6. The current coolant level is either at what is shown in the picture or just slightly above it. This level has not seemed to change the last couple times I drove the car but somehow it is still spitting out coolant through the overflow hose. 7. I have not tested the cap. If I remember correctly the kit I have does not work with testing that cap or there was some sort of other issue. With the heater not working and it continuing to spit out coolant it really seems like evidence is pointing to an air bubble being formed and I would imagine continuing to get bigger. I will try opening up the radiator bleeder today. As stated one element I have not tested is the radiator cap. Could a bad cap cause such symptoms? Thanks everyone.
Mike32, there is no leaking around the water pump. I am wondering if the Mondial is all good at this point as on today's drive the heater was working, the temperature held at about 80C, the and only very minimal coolant came out of the overflow. I am wondering if this has just been a couple months worth of the system sorting itself back out to the proper level. If there is any other insight please share and if there are any other thoughts please do the same.
water colling systems only sucks air, when you have a leak, probably while hot ! (with thermostat open). what happens is: 1) you turn on the car, there is no leak because its cold 2) you heat it up, the thermostat opens and the leak ocurr when you are driving 3) water just dissapears in the road, so the leak is also used to suck aire due to vacuum 4) then you stop the car, wait until its cold and thermostat closes again, you test, and you are testing nothing.
I'm not sure if your Mondial uses this, but most of the HVAC systems of this era used what's called a "Monovalve" made by Bosch. It's basically an electrically operated heater valve. The climate control system will cycle this valve open and closed to set a specific temperature. Oddly, voltage keeps the valve shut, not open. These are quite common and were used in cars from VW all the way to Mercedes and even Bentley. Surprise, surprise, they fail over time. These can be rebuilt, but the rebuild kits are garbage. You can replace the entire valve with a American made one that will bolt into place (superb item: Heater Control Valve | BMW 64111373188 | Rolls Bentley UR27683 | Ferrari 61079000 | Klima BVX-6 – Klima Design Works (klimakit.com). For the time being, just unplug the electrical connector. If the internals are not jammed shut, it should start to flow hot coolant right away. The valve most likely will be located under the dash board on the passenger side of the car, mounted on the wall of the wheel well.
The Mondial 3.2 at least uses that valve. It was also used on BMW 5 series of the period and I have rebuilt them on both my 533 and Mondial and the kit worked well and has lasted at least 12 years. Peter is correct that they fail open, but they also have a screen in them that gets clogged and blocks flow. On the BMW it was on the firewall and took about 10 minutes to do, no draining required. On the Mondial it is in the passenger footwell and is absolutely hell to get out and can't be repaired in place.
Did you use the original Bosch kit? Apparently they do last a very long time but Bosch discontinued them years ago and it's the aftermarket replacements that fail (according to all of the reviews on various vendor's websites, like Pelican Parts, Amazon[!], etc). I've noticed a few NOS rebuild kits come up for sale on eBay, but they were $400+. I went with the Klima unit as it was half the price. To me, it looks like they sourced a Ford solenoid to operate the valve (very similar to ones used in newer pickups). Yes, RPITA to work on in the Mondial Image Unavailable, Please Login Image Unavailable, Please Login Image Unavailable, Please Login ...
