Folks, on my 2005 s type 3.0, I have a small coolant leak that so far have not found. It does not appear to be coming from anything on top at all. When parked for hours a small puddle is found beneath the front passenger side seemingly under the radiator. With flashlight, the radiator does not show any evidence of leak on either side but the belly pan does show some moisture almost directly under the climate control module. The module is newish andI can see it is dry. I believe the leak is lower than that. So my question is... what fittings are on the radiator at the bottom on passenger side that I am not seeing? Or any other suggestions appreciated. Thanks.

 

My guess would be the plastic side tank on the radiator is split close to the DCCV.
It seems to be a fairly common failure.
Take the undertray off and try and get a good look at it, maybe a pressure test.

 

I was unaware of a plastic side tank.??? I have a plastic reservoir tank on top which commonly develops a cracked nipple on the return line, but mine is new. Are you saying there is a second plastic tank on the car?

 

Take off the undershield and look.

 

Yes, but it's part of the radiator. Have you checked the connection on the bottom of your new tank?

 

I had a leak earlier this year in that location that grew fairly quickly into a bigger leak which needed topping up after every journey.
It can be a combination of things leaking. In my case the radiator was leaking at the top due to corrosion near to the expansion tank although the expansion tank was ok and that is a regular source.
The top hose was also leaking and the plastic piece in the middle of it had been glued together too many times so that it fell apart on removal of the top hose.
I replaced the DCCV valve as advised by the forum experts at the same time.

The cold pressure test showed nothing. The leak seemed to be when the engine warmed up after a run. Now I top the coolant up every few weeks with a small amount only as I would expect for a car of this age.

 

Jagv8 is straightforward and made me chuckle..."take off the undershield and look"... I plan on that this weekend. I was just hoping someone would offer a similar experience. Yes, the hose connection into new reservoir is secure and dry. Nothing on top shows any leak, but I must admit it is peculiar that on the top of the new reservoir tank by the infamous nipple and facing the throttle body, there appears dry, salt-like residue that wipes right off with finger. I'm attributing that to coolant mist from the fan being blown up there and evaporating off. But it is weird that this white residue only appears right there. I appreciate further comments and suggestions on this issue.

 

If you have a dried-coolant trail...that changes things...otherwise, I'd say put it up on ramps, pull the undertray, and crawl under while it's idling and you'll probably see a drop or two escaping the radiator side tank seal as Norri described. If you see a dried coolant trail on the DCCV, you still need to fire it up and have a look. I've had two leak in the exact spot and it blows onto the DCCV.

Just because the expansion tank is new, doesn't mean that nipple can't leak....have you or anyone servicing (or gawking at) the engine leaned in inadvertently on it? Doesn't take much...

 

Thank you for replies. Yes, I know about the fragility of that reservoir nipple and I have looked and looked at it. I am pretty sure it is OK there. It occurred to me that maybe the cap itself is not sealing and allowing a really small vapor leak up there but I can't see anything wet escaping with the car hot and shut down. I'm thinking it's leaking really down low because the dccv is dry and no dried coolant on it, but directly below dccv, the pan appears moist and it is right below the dccv that a teaspoonful or so collects on the garage floor overnite. Can anyone attach a drawing or spec on the plastic side tank that some are suspecting please. Appreciate all help.

 

Can anyone attach a drawing or spec on the plastic side tank that some are suspecting please. Appreciate all help.[/QUOTE]

The plastic side tank is part of the radiator assembly. As far as I know they are not replaceable. The complete rad needs changing.

Happened to ours exactly where your leak is.

 

Definitely not replaceable, or at least weren't a few years ago when I attempted to have it done at a radiator shop that had performed a similar service on my (much larger) diesel Excursion radiator for less than $100. They cleaned it, pressure-tested, found it leaked exactly where I said, looked all day for parts and told me they couldn't help me and there'd be no charge. However, since then, in very recent times, from what I can tell, some internet merchants are advertising radiators with the integral transmission coolers necessary for the automatic transmission for less than $200. Used to be, ALL of the $150 range S-type radiators advertised were for the manual gearbox application, sans integral cooler.

I have 2 that I've taken the plastic side-tanks off of in preparation for scrapping...I could snap you a pic of where the leak likely is....but the tank is long-gone (when I say "taken off" I mean with an air-powered chisel...it wasn't a bolt or clamp arrangement.)

The black plastic bits are what we are calling side-tanks. In this shot of a new one, the leak is likely about 3/4 of the way down the right hand side, at the crimp, on the face toward us:


No side tanks:


Have you clocked somewhere between 100K - 110K miles? (that seems to be the lifespan, in my experience)

 

180,000 miles. In my case, the body and interior of this car are still showroom. But numerous nickel and dime stuff that I keep repairing myself with mostly success. Not in position to get into new car payment and this one is paid for. I have an extra car for backup use when I work on this one. Getting old though.

 

Well then, Norri and I would say you got extra mileage out of yours, if, in fact, it turns out you have a leaky radiator. Don't know much about MBC's experience as to mileage and leak rate, but in both of mine (103k and 105k, I think) the leak was a small drip that resulted in a low-coolant indication about once a week (one was daughter-driven out-of-state at college) and I could find neither until I had it up in the air, pan off and idling.

Good luck, and don't forget to update us when you find the culprit.

 

Thank you very much for responses. I will update when I get under it and hopefully find. If this was a weekend hobby car, wouldn't be so stressful. But unfortunately it's wife's daily commuter and she refused to let me take her car shopping. We are in senior years and taking on a car payment doesn't make sense anyway. Oh well, I've become a mechanic with this car. I have pulled front end off to change both headlights, intake manifold to do IMT rings and coils and plugs, upper reservoir twice, serpentine once, numerous brake jobs, mafs a couple times, fuel filter, changed the accelerator pedal due to fault code, and more I can't think of. I'm hoping I don't have to pull the radiator. Seems complicated from visual.

 

I had to pull the radiator shroud last summer to get to the fan. I didn't need to remove the radiator, but it looked pretty straightforward once the shroud was out of the way.

The only difficult part was removing two U-shaped metal clips at the bottom of the shroud securing it to the radiator. If not for the clips, the shroud would have easily lifted out once the top was undone.

I vaguely remember a little cooling duct for the fan controller. It ran under the horizontal plastic shelf behind and below the grill. It was secured with plastic rivets, the type with a locking pin through the middle. To reach one of them, I think I used a long skinny screwdriver fed through the grill. Not 100% of the memory, but I think that was it.

 

Hmmm....I thought the design-intent of the clips at the bottom WAS to be able to lift it out after you'd undone the top? (or more properly, for assembly, at the factory, to lower it into position and secure the top, without having to do anything at the bottom)

I've done 2, can't remember messing with the clips at the bottom - that's not to say I didn't, just that I don't remember it. I DO remember a couple of troublesome items from the radiator R&R: The constant-tension hose clamp on the LHS of the radiator was clocked to a near-impossible-to-squeeze location (even for the flexible-cable clamp tool!) and that same hose-nipple, does not clear the a/c lines on either removal or installation, regardless how much you tilt or clock the radiator! You have to "tweak" (some say "bend") the line slightly to get it in and out. Otherwise, it is not a particularly heinous task.

 

Just getting back to everyone letting you know I have not had time to get under the car to investigate further. Holidays cramping my time. Car is parked for a few days now so I will get back into it after Christmas day. Thanks for trying to help me so far. I will report back next week. For now.....Merry Christmas To All!!!!!!

 

Update on this mysterious slow coolant leak. Guys, I finally had time to pull the belly pan and get underneath it. I discovered that I am still at a loss as to the source of coolant leak near the right hand side under radiator. Everything is dry above the dccv, and only evidence of a drip from beneath the front pan that connects to bumper. The black plastic "tank" that sits on the side of the radiator has a moist surface near the bottom, but observing the entire area with a bright flashlight and with engine hot and running or off, I can not see anything actually leaking. Whatever it is, it is very slow at this point because the coolant level in top reservoir barely drops over a couple weeks, and I simply add maybe a 1/2 cup of coolant to bring it back up enough to cover the"low coolant" sensor in the reservoir. I appreciate any further ideas, but I guess I'm on a watchful wait on this issue for now.

 

My money is still on the rad, I was working away when mine started leaking and it took quite a while to track it down, during that period it just took a minimal top up now and again to keep the level good.

 

Thank you Norri. I'm thinking you're right. Just trying to avoid getting into it at the moment.