coolant system help

piattteam · Aug 30, 2012

Hey all, our coolant system is messing up and hoping to get some help here.
The coolant heats, goes into the overflow tank just fine.
Problem is, the system isn't sucking the coolant back out of the overflow tank, into to radiator.
Runs 10 degrees warmer than usual, but doesn't over heat.
We have replaced the cap, incase the vacuum release check valve was bad.
Thanks all!

BobWolf · Aug 30, 2012

What are the details on the truck? year, make, model, miles, and engine details. Some trucks have thier own deomons. I would first check the engine oil fuel and coolant to see if any of the three are mixing. Oil in coolant looks like a slight slick barely visable to a couple small drops after sitting a couple days to totaly contaminated Milkshake, strait oil. Keep in mind a small ammount is the norm for high milage engines and crud in the air getting sucked in through the cap. but usualy no more than a light film to a small drop or two after sitting for the weekend seen now and then through the filler so dont panic if you see a small ammount of oil in the resivor as long as your temps are reasonable this is somthing you just keep an eye on.

Check the exhaust pipe and see if it is wet this is bad usualy means a bad EGR cooler and or pulling the head. I would recomend picking up a cooling system pressure tester and adapter this can tell you if you have a bad hose, gaskett, or seal or other part. Change the fuel filter pour the fuel into a clean, dry mason jar colse it up let it set for a couple hours if you have coolant in the fuel it will sepperate fuel will float on the water. Remember that this may be water from the fuel its self and not coolant. If your in doubt pick up some fluid test kits from a shell oil distributor abbout 15 bucks plus or minus and send in oil, coolant, and fuel samples they will tell you if its all good.

Hoses, seals, and your radiator will get pourus with age. If you are the proud owner of a plastic and aluminum radiator you may have a tank seal going bad all metal units can be resealed by a radiator shop if the rest of the radiator is in good condition. A bad T stat may be the problem but the coolant has to be somwhere if you had a recent coolant change and luck be on your side you might have an air lock this is usualy fixed by idling the engine heater on hot setting and you should have a bleeder valve to crack open to bleed air out.

Shoot me the details so I can help or terrify you more ofcorse I want to help.
Feel free to give me a call 585 414 7732 8 AM

8 PM Eastern It may be quicker and easier to walk you through tiis by phone than online.

Bob Wolf

piattteam · Aug 30, 2012

Thanks Bob. Just had EGR cooler replaced in June so that should not be the problem. I will try the bleeder thing in a few minutes. I will let you know.

Turtle · Aug 30, 2012

When the engine gets warm the coolant expands, the pressure regulator (usually the radiator cap) allows it to expand a specific amount to raise the pressure and the boiling point of the coolant. When it over pressures, the regulator (usually the cap) allows coolant to flow under pressure into the overflow reservoir bottle. Then, when you cool back down, the coolant contracts creating a vacuum that sucks the coolant back into the radiator. If the coolant doesn't flow from the reservoir, there is a leak somewhere in the system that's pulling air instead of coolant during cool down.

Sometimes the cap to the overflow tank cracks with age and allows air into the return/suction line. I would check for an air-tight seal in this part of the system first. Might be a bad thermostat. There could also be a clog somewhere in the radiator, which can affect the abnormal operating temperature, and the pressures inside the cooling system. Might also be a failing or failed fan clutch, which if stuck in a lower speed mode, or isn't turning freely, can make the coolant run warm.

I would check for pressure leaks first, because that's the likely cause. Then radiator clog (at operating temperature, if one side of the radiator is too hot to touch but the other is cooler, there ya go), then the thermostat, and then the fan clutch.

And of course, it could also be a blown head gasket.

purgoose10 · Aug 30, 2012

This may be for another thread but wondering why more owners don't use Evans coolant?? All my trucks use synthetic hoses and Evans coolant. Doesn't boil or freeze. Uses no water just Evans, never have to service it. Expensive $25 a gallon but again never have to change it.
To answer your question, could be the small rubber hose is plugged or you have a leak in the plastic tank causing it to loose pressure.

Turtle · Aug 30, 2012

I don't use Evans coolant because the cooling system is the Sprinter is not designed for it and it is not recommended. In order to use Evans in a Sprinter I'd have to mod the system to make it into a zero-pressure system instead of the pressurized system. The coolant flow would alsol have to be increased with a different water pump, as well, since Evans does not transfer heat as efficiently as a 50/50 mix does. You have to move MORE Evans coolant per unit time in order to remove the same heat as water or 50/50 at a lower flow rate. One of the main selling points of Evans is that it gives you the ability to increase engine efficiency by raising the operating temperature of the engine (and with Evans it certainly does that), but with a Sprinter and it's aluminum engine that's really not something you want to do. You don't really want to do that with any TDI engine, aluminum or not. In order for Evans to remove the same amount of heat as water at the same flowrate it has to get MUCH hotter, which it does, and so does the engine. At colder temperatures below about 10° F, Evans has the viscosity of honey, which can present its own set of problems with an aluminum engine, not to mention the stress on the water pump and the head gasket (of which blown ones are rather common with TDIs using Evans).

Not having to change the coolant is certainly appealing, as the absence of water will more or less eliminate the corrosion and pitting that neglected 50/50 will cause. There are some cooling systems that are designed for Evans. Mine is not. Few can so easily just have their 50/50 coolant replaced with Evans, however. TDI engines do not have an overheating problem and engine part failures due to overheating under normal conditions, and that's because the cooling system is designed the way it is. You mess with that and you're asking for trouble. Since heat related failure problems with the Sprinter engine using the OEM cooling system are not a concern, I am content to spend my money elsewhere and focus my attention on the things that deserve that attention.

BobWolf · Aug 30, 2012

Glad to hear things worked out and it was an air lock not something major I try to remember to keep it simple before re-engenering. Anyway, chalk one up for the drivers and a big fat zero for the I.H. dealer parts installer. One more thing keep a gallon of 50/50 to keep the coolant full as the system will suck the coolant in and you may need to burp it a couple more times.

Bob Wolf.