Diagnosing low coolant in 2001 V70

[prwood]

I'm trying to diagnose a low coolant level on my 2001 Volvo V70 2.4T where there are no (obvious) external signs of a coolant leak. I'm hoping to rule out a head gasket leak early on by running a block test. So, I borrowed a block test kit from AutoZone ( http://www.autozone.com/loan-a-tools/bl ... 391378_0_0 ) and ran the test today. However, I wanted to be sure that my test results were valid, since this car does not have a radiator cap, as described in the testing instructions. Rather, I used the coolant expansion tank to do my test.

After having warmed my engine up for 10 minutes and allowing it to idle, I filled the tube with test fluid to the indicated line, inserted it into the opening on the coolant expansion tank, and used the provided bulb to draw gases up into the test tube. I did this for two minutes as suggested in the instructions, and while I did see bubbles forming indicating that gas was being pulled into the fluid, I did not see the fluid change colors.

To confirm that the apparatus and fluid were working correctly, I ran another test with fresh fluid on the output of my exhaust pipe, and the fluid turned yellow immediately as expected.

Does it seem like this was a valid test, given that I was working with an expansion tank, and not directly on a radiator cap?

If this test was valid, then it's time to move on to other causes. I have read that there are some external leaks that don't show any visible evidence due to the coolant being boiled off, or pooling into hidden areas, so my next step will be to start pulling things apart to find the source of the leak...

-- update -- added photo of setup - sorry, not sure why it's not rotated correctly --

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[jonesg]

Thats the correct way to do the test.
Water pump old?

I saw a UV dye test flashlight for $29, might have been harbor freight.

[jonesg]

Looks like the seams have dried deposits on that plastic expansion tank.
They only last so long.

[prwood]

Thats the correct way to do the test.
Water pump old?

I saw a UV dye test flashlight for $29, might have been harbor freight.

I don't know the age of the water pump. I bought the car in 2015, and I've been doing all of the service and repairs since then. I haven't replaced the water pump. The Carfax report I ran before purchasing didn't show any record of the water pump or cooling system being serviced, just that the cooling system was "checked" once in 2008. There's also no record of the timing belt being replaced, which from what I gather often also includes replacing the water pump. The Carfax record showed it having up to a 90,000 mile service from the dealer before we bought it, but after that it just shows oil changes and brake replacements up until I bought it.

[prwood]

Looks like the seams have dried deposits on that plastic expansion tank.
They only last so long.

I think I know where that came from. I was out on the highway about a month ago (I was already having low coolant issues at this point) when the 'low coolant' warning came on again. I pulled over and popped the hood and took the coolant cap off right away. Probably not the best idea. Initially when I looked in, the coolant did look low, but from there it jumped up, and hot coolant suddenly bubbled up and out of the expansion tank. It seemed to dissipate right away, but left the white deposits... and I just hadn't bothered to clean them off.

[abscate]

Your test procedure was perfect ( nice blank test on the exhaust!) but unfortunately these tests are definitive positive but indeterminate negative)

Your car should have had a new timing belt and hardware ( but not water pump) in 2010 based on time, but miles are " usually" more critical. I ran mine to 137k miles but that is really gambling with Satan. I had made a drive until death decision at that point, then found this website and learned that I actually could work on these cars.

[jimmy57]

How much coolant have you added total? A leak at heater core inlet/outlet pipe o ring can lose maybe 2 gallons and not show unless you pull carpet back and look. Unlike heater core itself leaking, this doesn't usually steam windows.

The block test checks for combustion gas in coolant. The crack at top of cylinder that can affect these engines doesn't always show with combustion gas in coolant until it is a more rapid loss with misfires on start.

[prwood]

Your test procedure was perfect ( nice blank test on the exhaust!) but unfortunately these tests are definitive positive but indeterminate negative)

So the only thing we can say for sure is that we still don't know for sure if it's the head gasket.

Are there any other tests I could perform, or symptoms to look for, that would more positively rule the head gasket in our out?

Your car should have had a new timing belt and hardware ( but not water pump) in 2010 based on time, but miles are " usually" more critical. I ran mine to 137k miles but that is really gambling with Satan. I had made a drive until death decision at that point, then found this website and learned that I actually could work on these cars.

Hmm. According to the Carfax report, it hit 100,000 miles before it hit 10 years:

• First mileage recorded: 15 miles on 3/1/2001

• Passed 100,000 mile mark: 103,202 miles on 11/28/2007

• Passed 10 year mark: 150,633 on 6/1/2011

The Carfax records from around the 100,000 mile don't indicate timing belt or water pump replacement, and from what I've read, the 90,000 mile service doesn't include that either:

• 8/13/2007 98,217 miles Notes: 90,000 mile service performed; Body electrical system, electrical system, transmission, wipers/washers checked; tires balanced; transmission fluid flushed

• 9/18/2007 99,847 miles Notes: engine/powertrain computer/module checked

• 11/28/2007 103,202 miles Notes: drivability/performance checked; engine/powertrain computer/module checked

After that point, there are no more records of dealer service. Between 11/28/2007 and 6/22/2010, there are records of state inspections and oil changes at a local Sunoco every 3-6k miles. From 6/22/2010 until I purchased on 9/19/2015, the only records are of state inspections. So, no definite indications that a timing belt or water pump service was *not* performed, but also no proof that it *wasn't* performed. Kind of like the block test.

That being said, the current mileage is 212,677, so even if it did have the water pump or timing belt replaced at either the 100,000 mile or 10 year (150,000 mile) marks, it seems like it's just about time to replace them anyway...

[prwood]

How much coolant have you added total? A leak at heater core inlet/outlet pipe o ring can lose maybe 2 gallons and not show unless you pull carpet back and look. Unlike heater core itself leaking, this doesn't usually steam windows.

I have added almost two gallons of coolant at this point. I can take a peek behind the carpet at lunchtime... I'm assuming that tools aren't required to move the carpet?

The block test checks for combustion gas in coolant. The crack at top of cylinder that can affect these engines doesn't always show with combustion gas in coolant until it is a more rapid loss with misfires on start.

I also borrowed a compression test kit. Would a compression test show a cracked cylinder?

[prwood]

I was able to examine the heater core. Here are my results:

* All exams were done with engine running, at operating temperature, with temp control set to heat.
* Didn't see any evidence of dampness on, under or around heater core or carpet.
* Didn't see any active leaks or liquid around heater core and fittings.
* Didn't notice any unusual smells, certainly not a coolant smell.
* Did see some dried white residue in a few places. Impossible to tell how recent it was, or if it was even coolant-related. I'll clean it up and check to see if it comes back.
* Heater is definitely blowing hot.

Photos: any comment on the white residue? I'm going to keep the trim panels off so that it's easier to examine the area, and see if anything new shows up after I clean it off.

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