Where is my coolant leaking from?

I have a 2009 Toyota Sienna with 80k miles. I did an oil change and saw a little carmel color in my oil. I checked my coolant resivor and it was empty. So for the time being, I topped it off with 20oz of water. At first I thought it was a BH but after talking to a Toyota Tech, he is certian that it’s not a BH since the car show no sign of BH. There is no white smoke, no over heat, or leaks on the floor or no CEL. What area can coolant leak into the oil besides the HG? I read that coolant can also go into the oil if the intake manifold has a bad gasket.

If by carmel color in the oil you mean foamy brown stuff that looks like chocolate milk, then unfortunately you may have a manifold leak allowing coolant to get in the oil. This needs to be addressed soon as antifreeze is a lousy lubricant and you can damage the engine rather quickly. Needing to add coolant adds to the suspicion of a head gasket. Not sure what BH means. An small leak early on won’t show as smoke or trip a CEL.

@SteveCBT, I think BH is his shorthand for blown headgasket. Most other site users use BHG. At least that is how I read it.

@MOVAN, how much caramel color on the dipstick or oil fill cap did you see? A little could be moisture from combustion or the air if your driving habits are many short trips where the engine cannot fully warm up. As long as the oil itself was not creamy. If the oil was creamy, then yes you have an internal coolant leak that needs to be found and fixed. First thing to do is run a cooling system pressure test to see if there are any obvious leaks.

Sorry, Yes I meant BHG…No visible caramel color on the dipstick or oil cap. No, the oil is not creamy, I saw a small amount on the surface of the pan. I drive about 20,000 miles a year so there is no short trip.

Is there a way to check for leak in the manifold or do I need to take everything apart?

You can have the radiator system pressure tested. If it was on the pan it would be an external leak, hose or water pump. I would have said radiator too, but you said residue was on the motor. The fluid can be tested for exhaust gasses to check for a head gasket breach. There is a leak down test that can verify if the head gasket is breached.

If it is not on the cap, dipstick, or oil, I doubt it is internal. This is good news. And if only 20 oz of water topped it off, it is probably a very slow leak. Monitor it and keep an eye out for the leak. A UV dye test can also help.

Sorry if I word stuff wrong on my last post…When I said I saw a small amount on the surface of the pan, I meant there was a small amount in the surface of the oil. The entire oil is not creamy, just a small amount that floated ontop of the oil pan.

Have a leak down test done. It will show if It’s the head or intake.

My information shows that the Sienna has an engine oil cooler. You might check that for leakage. While the engine is running the oil pressure would probably be forced into the coolant. This should show up as oil in the coolant. But when the engine is off the residual pressure in the cooling system would force coolant into the oil passages until the system cooled enough…

Hope this information is helpful and not a red herring.

You need an accurate measurement on how much coolant you are actually loosing. Fill your coolant reservoir to the mark, then check it daily, in the AM before you leave for the day. Over the course of a few weeks, this will give you some idea how much coolant you are loosing. On many vehicles the cooling system is vented to outside air at some point in the system, so some vapor loss is normal. If it turns out you are loosing a cup of coolant in 3000-5000 miles, that’s probably within the normal range. Also, you loose coolant faster immediately after a coolant change or there has been work on the cooling system, as dissolved air makes it appear there is more coolant than there really is.

Check the crankcase vents. condensation will accumulate in the crankcase if the PCV system is not venting freely.Engine oil contaminated with coolant usually looks like a chocolate milk shake left on the table overnight.

Thanks for all the great information. It’s good to have these information when I take my car to get checked. Since it’s going to be warm next week, I’m going to do a little poking around to see what I can find. But to answer the question about how much coolant I am loosing…I bought the van in October 2012 with 59,000 miles and I know for sure that the coolant level was full. To this date, at 80,000 miles, I had to pour 20oz of water to fill the resivor to full. So roughly, 20 oz was lost within 20,000 miles.

How about driving habits? A lot of short trips where the engine didn’t warm up all the way? Also the coolant loss may be recent or could be evaporation over the last 16 months. Keep an eye on it to see if you have any noticable loss over time.

An oz per 1000 miles is probably normal. That’s less than 1/2 cup in 3000 miles. It’s probably just evaporating to the atmosphere as BK says.

One caveate: It’s possible you have lost more than 20 ounces and don’t realize it. Since you’ve only judged this based on the plastic reservoir. Unless the radiator itself has been verified to be full.

My van has a remote starter so during the winter months, it’s always warmed up before I head out. I rarely drive on a cold engine. Also, It may be more than 20oz, I didn’t check the radiator to see if it’s full but I will keep an eye on it. It still dosen’t explain the small amount of coolant in the radiator. I will be checking the van this weekend to see if I can find anything before taking it in.

I used to have a 92 acura legend which is known for BHG. Mine was bad to the point where it would over heat and looses coolant every day. The oil was pure milky during oil change. It wasn’t worth fixing so I sold it. The oil in the sienna is no where close to the oil in my old acura legend.