As an owner of both an Acura 3.2TL and a Honda Pilot, I'm hoping this community can help me with a problem on my 2005 Pilot . I bought it new in December, it has only 5000 miles, but it is losing radiator fluid . I've had to add over a quart already and the level keeps going down . There are no drops on the garage floor and I can not find any signs of leakage anywhere under the hood . The vehicle almost never sees the highway and gets about 15 MPG.

I'm sure if I can find the problem it is covered under warranty, but I don't want to bring it in until I know what the problem is and that it is not something simple I can fix myself.

How can I find out where the coolant is going?

 

Since the vehicle's under warranty, why not just bring it in to the dealer and stop knocking your head against the wall? If there really is a leak and it's internal within the engine, the sooner they find it, the better.

 

Well...a compression test would tell you exactly what is going on. Most likely if coolant is being consumed internally, it's a head gasket. If you are lucky it might be an intake gasket, but you'd see the coolant or a wet spot somewhere. If there are no signs of an exterior leak (i.e. hose, water pump, radiator, etc), then it's going inside the engine. The engine can't burn coolant so it will appear as small white smoke out the exhaust.

If the head gasket lets go completely, you'll know!

LET THE DEALER LOOK AT IT.

A-Train

 

A used oil analysis would likely tell you if you have an internal coolant system leak. I'm not sure what additives Honda uses in its coolants, but I think you'd look for a high level of coolant additives like Boron, Sodium, Potasium, and Magnesium.

At the "Bob is the Oil Guy " website (aka BITOG), there is an offer to get a UOA with an analysis of the results by Terry Dyson, a recognized expert. If you go this route and the results show that you have an internal coolant leak, it would arm you with supporting evidence when you finally take the Pilot in to the dealer.

Why not just go to the dealer and let them handle the problem? You'll have the issue on record and they will likely first look for small evaporative coolant system leaks that occur when the engine is at operating temperature. If they say the coolant loss is normal or they can't find the problem, then you could drop the $40 on the UOA.

 

Have you looked at the oil? Does it look like chocolate milk?

When the car is warm, does the radiator cap have pressure on it?

I common place (on older cars, not so much on newer) for radiator fluid (otherwise known as coolant) to leak is out of the cap if it is not holding pressure. The fluid will slowly evaporate. The radiator cap could be bad or just loose.

 

Problem with pressure tests is that they don't detect all leaks, often times, only large leaks are exposed with pressure tests.

UOAs are worth a consideration, though from an OEM standpoint, 3rd party labs are quite inaccurate (I don't disagree) and the engineers may not use them as a basis for tearing an engine apart.

If you're losing that much coolant, try changing the oil. With the amount of coolant you're losing, the coolant should overwhelm the oil's add pack and "fall out" of suspension, into the bottom of the oil pan. Thus, when you change the oil, you should be able to see some coolant come out immediately after pulling the oil drain plug.

Mike

 

In case anyone misunderstood -- I'm not suggesting a pressure test. The radiator cap needs to hold pressure (~15 psi usually) to keep the coolant from boiling and thereby evaporating (since cars run above the boiling point of water at 0 psi at times)

If the radiator doesn't build pressure (careful when testing this)

a) you've got a large enough coolant leak that pressure can't build (you'll see white exhaust or milky oil on the dipstick)

b) the radiator cap is bad/loose.

If the second case, easy fix!