Coolant Loss, maybe Head Gasket?

i know this is an old topic but i am having the same issues with my prius.nobody can find any problems with the car yet it keeps losing coolant somewhere.

i have been driving the car for about 10k miles since problems started.adding coolant when the triangle and thermostat comes on.

i'd love to know what the problem might be .

 

A few questions:

1. How many miles on the odometer?

2. How low is the coolant, when you refill it? (Since you know a problem exists, I strongly suggest that you not wait until you see warning lights come on, before you check and refill the coolant.)

3. How many miles do you have to drive, for the coolant level to drop to the low level that you've observed in #2 above?

4. When you say that "nobody can find any problems", who is the nobody, and what has that person done to your car so far?

The usual test would be for the mechanic to apply pressure to the engine cooling system by attaching a radiator pressure tester device to the radiator cap opening. Then see whether the system will maintain pressure. If it maintains pressure, then there should be no leak.

If the system does not maintain pressure, look around for a coolant leak. Typical places would be a failed rubber radiator or heater hose, a leaky radiator, or a failed water pump. Usually you'll see a whitish or pinkish stain from the antifreeze at the point of the leak.

If the head gasket has a problem, you will usually find coolant in the engine oil (which makes the oil look milky) and/or oil in the radiator (which will be floating on top of the normally pink antifreeze). Do you see signs of either problem?

 

I tend to look for simple first. Try checking and or replacing the little tubing from the reservoir bottle to the rad cap. I know my daughter's 02 Camry was losing a little coolant and that was it. It is often overlooked but a very important part. It fits going from very cold to very hot excercises the coolant reservoir more.

 

A used oil analysis will uncover coolant in oil long before it gets to the frothy-milky-sludged-up-oil stage

 

1- it has over 350,000 miles

2- we add less than a quart of water/coolant

3-around 60-70 miles

4-we took it out to the dealer and they checked and conculuded that it might be the head gasket.but cant be sure of it.

this car has been driven like this repeating problem almost 10,000 miles now.

i wonder if there is anything i am missing before i go the head gasket way.

it currently has p0420 code for catalytic converter.could it be somehow related due to backpressure.

cheers.

 

350K?? On an '06? That's astounding. What kind of duty does
this car serve, out of curiosity?
.
_H*

 

I can't believe your engine is consuming a quart of coolant every 60-70 miles without some driveability symptoms - and that you've driven the car like this over 10K miles. Do you see engine oil in the coolant, or coolant in the oil, or white smoke in the exhaust when you rev up the engine (that would show water vapor is present and confirm the head gasket is leaking)?

At 350K miles, I would say forget about replacing the head gasket, and instead install a salvage drivetrain (both engine and transaxle) from a low mileage vehicle - if you want to keep the car.

You should also replace the catalytic converter, air/fuel ratio sensor and oxygen sensor to address the P0420 code. Good luck.

 

Help request.

375k miles. ICE coolant system builds pressure, overflow tank overflows. Replaced water pump. No change. Concerned I couldn't bleed air out completely, took it to dealership, they replaced thermostat, radiator cap, and coolant then completely bled. Sloshing behind dash gone, for a while.

Issue continues. Bought that HG test kit, where the blue turns to yellow IF gasses detected. None detected. Finally, bought a generic 16psi radiator cap (stock is 13psi). That helped a lot. However, if driving up a hill it will still overflow. Leak-down test kit at store has not fittings that seemed to work... however get this, I can go out there after car sits for 2 days and is stone cold and cannot remove cap without it wanting to puke, not air but coolant!

CLUE #1
When doing the HG test I noticed something strange and now suspect a clog but I get no such codes... anyway when you REV and fill with Lisle funnel, it takes in as much coolant as possible. As soon as the computer says it's time to drop RMPs and idle to charge battery, it BELCHES UP into FUNNEL about a full water bottle of coolant... why?

SO it seems that while water pump is spinning at higher RPMs there is pressure being built, and the puking occurs upon slowing the water pump. Before I explore a complete motor RNR I would love to know what could be the issue, is a component (radiator, 3 way valve, ?) can be replaced to cure this issue, I would proceed that way as there ARE NO DRIVABILITY ISSUES WHATSOVER. I'm still driving it, I added a small motorcycle overflow bottle under the hood, attached to the stock overflow cap/hose. So I loose no coolant this way, but when I loosen the radiator cap to replenish, it's as if it's held that 16psi of pressure so I loose coolant just by removing cap, no way around it.

Catalytic converter, cleaned it myself, it was 2/3rd clogged and now, 90% cleared. Symptom was power surging, now has full power and better mileage. I had considered that the back pressure was somehow causing the issue.


CLUE #2
There is no sludge on oil cap, no oil in water, no water in oil, zero steam coming from tail pipe. Starts and runs great, no misfire felt, no misfire codes. No leaks anywhere in the system. No odor of coolant. Heater works perfect.
Once it's pushed enough coolant out though, the sloshing noise is detected again.

CLUE #3
Codes I've had are:
P0420, which is catalytic converter threshold below efficiency (OK, 375k miles what do you expect)
P0441, I don't see how EVAP components could effect issue
P0446, again, EVAP vent control. Probably an old vacuum line
P1151, see below

Note that the P1151 has not returned since dealership bled the system. Motor running thermos sounds like new.
I do have the Techstream SW & Mini VCI and have run the pump manually 6 times when I was trying to bleed unsuccessfully. It was very helpful, the first 5 runs of the pump produced bubbles up the Lisle funnel.

Ultimately, I could accept that gasses are passing through the HG or a crack, I would think a plug would foul or pressure would relieve itself though that breach. So I'm just not ready to go there yet. And, it's as if it passes it's own self-imposed leak-down test. It simply doesn't create a vacuum and suck the overflow contents back into radiator ever.

Any help (Patrick?) greatly appreciated. THANK YOU!

 

I would start by performing a cylinder compression test, which you can easily do since you have Mini VCI. You just need a pressure gauge which screws into the spark plug holes once the plugs have been removed.

I would also check the hose that leads from the radiator to the overflow container to ensure there is no blockage in that path. For example, apply compressed air to the hole in the radiator neck which leads to the hose that goes to the overflow container. Look for bubbling in the coolant in that container.

How well does the cabin heater work in producing heat?

 

Produces great heat, I would have to allow it to push at least a water bottle full on top of a maxed out overflow tank before heater is effected, and this would be due to lack of coolant or and too much air consequently.

The hose from rad neck to overflow is unobstructed, not cracked, not leaking. When I had the 13psi cap on, I learned to blow on the hose that comes off the overflow tank lid, while cap is off, to put the pushed out coolant back into radiator! It takes very little effort/pressure to blow it back into the radiator.

I guess the compression test is next, not sure when I can get the tools on loan from auto parts store (hoping the have something that will fit, their rad leak-down kit was of no use whatsoever, no adapter would fit the Prius).

Thank you for your reply Patrick, however, I was hoping to explore some sort of blockage, since the pressure builds ONLY after DECELERATION (as if the spinning water pump is creating the pressure against something, and when you let off the gas and RPMs drop, THAT's when the puking up (not bubbles, actual coolant) occurs.

 

[ ICE coolant system builds pressure, overflow tank overflows. Replaced water pump. No change.
Issue continues. Bought that HG test kit, where the blue turns to yellow IF gasses detected. None detected. ]

I have this issue on my 04 prius with around 400k miles with the same negative HG test kit results. I was able to do a leak down test to the radiator, pressure dropped at a rate of 2 psi per minute (from 13 psi) . I couldn't find the spec for this, but am guessing that's a fail. This being winter time, I'm not sure if the exhaust has more condensation than normal, the overflow tank overflowing is really the symptom. I've been draining the overflow tank back into the radiator, and am now running the system a bit low on coolant to slow down the coolant overflowing, but this really will only work when the temps are low, or until it really fails. I am guessing a failed head gasket despite the negative HG test. Coolant seems normal in appearance, engine oil may be getting black faster . I am curious if brokerdelete has an update to his problem. I do like to do my own mechanical work, but it's cold out, so I'll put off any repairs for a while.

 

I suggest a cylinder compression test would be useful to determine whether there is a mechanical problem with the engine.

 

Did you ever find out if it was a head gasket or not? I have the same problem with my 05 Prius and I'm curious.

 

Nate and BrokerDelete: Have either of you figured out where the fluid is leaking? EGR cooler? throttle body?

 

Gen 2 does not have an EGR.

 

Very old thread but seems to be a trend in bumping it. I am also experiencing coolant loss with no signs of leaks and all tests explained above performed with passing results. Figured I would bump the thread and as OPs to share their fixes (if any) before creating my own thread.