engine coolant level
 

Hi, a quick question re coolant level.

I had a bit of a fright when son borrowed my xc90 my2003 d5 driving about 40 miles.

I did have coolant level issues about 6 months and 3000/miles ago diagnosed to the radiator which was replaced and since then, no issues.

Son returned car saying that the 'coolant low' message displayed a couple of miles from home. I looked at this the following morning and the resevoir was empty and on ignition, red warning and stop engine message displayed.


I refilled to the mark and all appears well. But now very wary. Car in at the indi tomorrow for pressure testing.

I do notice that once the engine warmed and driven a few miles, the level drops about 3cm.

When cold, usually the next morning, releasing the resevoir cap, there is a release of air pressure and the level returns to normal.

I understand that there remains pressure in the system even when cold, but is this normal?

I have had lots of cars in the past and to be honest never had coolant issues so not sure if this is normal operation.

I just wonder if the large radiator pipes have become flexible with age and thy are now expanding under pressure and may need changing.

Any advice would be appreciated.

Many thanks

If you can hear air releasing when you open the cap in the morning there is no pressure loss so it would appear the cooling system is fine. A pressure test is done to determine leaks in the system both internally and externally.
As for the drop in level when engine warm, the thermostat opens up and allows coolant to circulate around the engine and heater system etc.Thats why you should always check level cold.
The initial level drop could be that there was an airlock after the rad was changed.
I would be surprised if you had a problem.

I have the same - coolant level light came on and I found it was indeed low (several centimetres). Topped up and has been a week now but level fine; this w/e checked all hoses, rad and ran with cap off to look for bubbles but nothing - all fine. So I am in similar position where some coolant has gone somewhere but now hopefully stopped, but am watching closely!

Did have same issue with my reliable but old Galaxy - same level for years then suddenly one day had dropped an inch or more; topped up and has been fine since.

Failed water pump seal, any dried coolant crystals?
 

Our D5 XC90 did the same for ages. It was only when we did a timing belt service that we found dried coolant crystals covering everything. It's really easy to pull the black plastic timing cover off to check, it's a single 10mm bolt and a handful of clips. Since you're in there check all of the tensioners and pulleys for dried bearings including the alternator pulley. Ours had a dried bearing on the plastic timing pulley. It sounded like a high pitched whistling sound, like a boost leak, but changed pitch with the RPM.

Amazon had the Aisin water pump for £45 a little while ago. It was identical to the genuine Volvo part we took off only the Volvo markings had been ground off. Hope you sort it soon.

Thanks for the responses. Timing belt, water pump, serpentine belt radiator all replaced within last 5000 miles.

My local indi pressure tested and checked around today. Still remains a mystery.

Will just monitor daily and see how it goes.

Thanks again for the responses.

John l

A quick update and the plot thickens.

I appears to have a problem leaking coolant only when my son borrowed the car for short trips.

It was a warmish day lat week and I turned the heating off. I since lost coolant to within about 2cm of the bottom of header tank with warning message that coolant was low.

Coincidentally my son likes a cool car and when he borrows it he invariably turns the heater down. Invariably the car then looses coolant.

I never see water in the nearside foorwell. There appears no leakage from.the hoses entering the bulkhead.

As mentioned in earlier post I have a new radiator fitted and again no fluid loss under the car.

I do understand that there is a heater matrix on the inside of the bulkhead and pipes pass through the bulkhead to this heater matrix.

When the temp controla are turned to zero, is there a valve which reduces the flow of water through the matrix? If so, I believe it may be this valve which leaks when switching from hot to cold only. When it is either in a fixed hot or cold position it appears to be fine for months. It appears only to leak when transitioning.

Does this make sense, anyone had a similar problem, does such a valve exist and if so, where is it?

Cheers john l

There is no such valve. The coolant always passes through it

Coolant can only be lost through leaking outside the engine or inside the engine

Check engine oil for coolant
Check transmission oil for coolant
Check you are not consuming coolant through a bad head gasket
Remove under-engine panel and clean it, then refit and drive for a couple of weeks, remove and look for fresh oil/coolant stains
Remove under-engine cover and park over a clean sheet of cardboard, see if anything drops down
Remove timing belt cover and look for leaks around water pump

Hi, old thread, but still a problem. Car has been serviced since, no problems found. I asked my Indi to check water pump and around the head but no problem. I since replaced header tank with new.

I also added UV tracer to coolant. A drive of about 20 miles and coolant seems to have been forced out of the bottle. The trace was all around underneath the expansion tank. The cap was new at same time as the tank so I can only think that I have excess pressure by a failing head gasket pushing air into the waterway. No UV trace in the oils.

Sometimes the coolant level (when stopped) seems to be way too high, but then settles back after a short drive and then too low.

Does this make sense? I do see an occasional bubble when engine is started and cap off the pressure tank. I believe this could well indicate a leaking cylinder head.
.
So, next job planned is new head gasket.

Here's hoping

Before you go ahead and replace the head gasket there are test kits you can buy that will inform you if there are any combustion gases in the coolant. They don’t cost a lot so are worthwhile doing first.