Hey all, I'm on several car forums and pretty good with a wrench but totally new to working on Volvos (mostly Japanese and VW cars in my history), just wanted to run something by you about my grandparents 1999 S70 (non turbo).

They bought it new, has 74,000 miles on it and always take it to the volvo dealership (the last 4 years anyway). While I was in town I just wanted to make sure things were caught up since I couldn't find their service records. I was poking under the hood and noticed the power steering was low and the coolant looked pretty dark. Swung by the dealership for some PS fluid and coolant.

While there I inquired about past work and according to them the coolant was flushed ~20,000 miles ago. I still wanted to flush it and confirm my suspicions. Opened the drain plug, and what came out was a deep green and black mixture (wish I took a picture). They seemed to separate, black settling on the bottom. I thought maybe it wasn't as bad as I was thinking, but as I was draining it, the settled mixture darkened substantially. It doesn't look like oil from what I've seen before, more like a black sediment.

After flushing with distilled water I opened the volvo coolant to find it's blue and not green, so my two guesses are at some point someone flushed/mixed it with non volvo coolant (has volvo coolant always been blue? does it become green with age?) or that the linings in the hoses are deteriorating or a combination of the two. I highly doubt a head gasket leak, it's literally driven by a little old lady. It's still got a while to go before it's due for an oil change so I don't know what the oil looks like, but again I don't think it's oil mixing with the coolant.

Any thoughts or am I making something out of a typical situation? I'm used to the light green coolant (prestone) in other cars that just looks like a dingy version of itself when it gets changed, this was a deep black which makes me wonder if there's something that needs attention.

Thanks!

PS- this car was so much easier to work with than my current VW Passat that manages to always leave me running to the store for some new tool. I did everything on this with a multi-bit screwdriver!

 

The Volvo coolant is blue, Pentosin. Probably got mixed with green somewhere.

 

I have this exact same car but mine has 150k. I'm thinking you might be due for a new timing belt and water pump at 74k (just to be on safe side) but given the color of the coolant I would be inclined to have it checked for a blown head gasket first. Are you getting any white smoke out of the tail pipe? Not sure if you know this but there is also a coolant drain at the back of the motor on the passenger side. It's a drain hole that is connected to a metal pipe that looks like a large brake bleeder. Seems to drain the water pump area. You might want to drain fluid from that point also.

 

Are head gaskets a common problem on the S70's? No white smoke from the exhaust. I know on the Passats there's an oil cooler that can cause the two to mix. If there's something similar on the S70 I think that would be more likely.

I'm still leaning towards the hose linings breaking down, but that's just a guess.

 

Head gaskets aren't as common a problem as people think they are. There is an oil cooler. It's on the side of the oil pan, and I have seen them fail, and that would cause oil to mix with coolant.

 

Pretty sure any oil in the mixture would float to the top. Is is possible that it is some type of aluminum corrosion byproduct?

 

This is a good point. Oil would either float to the top or emulsify with the coolant into a sticky, brown, milkshake- like substance.

 

That's been my experience with cars that have oil in the coolant as well.
As I said initially, it doesn't seem like an oil problem.

I've also thought of the possibility that is some type of aluminum oxidation as well (possibly a reaction from someone mixing non volvo coolant).

Again I wish I took a picture. At this point considering the car runs fine otherwise I will keep an eye on it and assume I'm making more of an issue out of it than really is, unless someone has had a similar situation and can speak to any issues it has caused.

 

Actually, after thinking about this for a bit, check your gound connections. There should be 2 ground straps attaching the cam cover to the firewall, as well as the battery ground cable. Black deposits could likely be from the insides of the hoses being degraded by electrolysis. Also, highly acidic coolant mixtures can cause it as well. Make sure you flushed the system well, and used distilled water. It's been my experience that any of the HOAT- type universal extended life coolants work well in these cars. Don't use Dex- cool or Pentosin G12. (why someone would put G12- it's pink- into a car that doesn't require it is beyond me, 'cause it costs $20/ 1.5L bottle, but it's got to be said)

 

Just wanted to also suggest you look into replacing that 13 year old timing belt. Not a fan of replacing water pumps that are not leaking. Yes these cars are designed to be easy to work on. The tools that come in the trunk can take care of a lot of the work.

 

Yeah, I'm planning to look into replacing it. Forgot to get a quote from the dealer (I know it will be pricey) versus ordering the parts and doing it myself (depending if and when I have time to do it).

Any recommendations for Timing Belt kit retailers?

 

I noticed all the grounds but didn't really inspect them. I emptied the radiator (at the time I couldn't really get too far under the car so I didn't drain the block). Added a gallon of distilled water and drove it for the afternoon with the heat on to mix with the heater core. Drained the radiator again and refilled with coolant and distilled water. Not a full flush but I figure it changed out at least 70% of the coolant. Really I just wanted to see why it was so dirty in the first place, and knowing a timing belt job is in the future it won't be long until I'm draining and adding more again. I'll see how it looks then (or mention it to the shop if I don't get to do the work myself). I'm also planning to check the hoses.

I'm familiar with G12 and it's not cheap (though volvo coolant and PS fluid wasn't either), it's what I'll be adding to my Passat (also in need of an "early" timing belt change)

Thanks again for all the help.

 

Good that you know to do the timing belt early on the Passat. NEVER wait the 105,000 miles VW says to. I just rebuilt the head on my wife's cousin's 99 Beetle 1.8T with 97,000 miles because the timing belt tensioner lost its oil charge and the belt got stripped. Had to replace all the valves and all the lifters. I don't think I've ever seen one actually make it to 105,000. Actually, of all places, get the kit from FCP to do the timing belt- their kit upgrades it to the newer, better tensioner design. (I'm assuming you have a 2000 or older car, with 1.8T)

As for the Volvo coolant, I've never used it- it's needlessly expensive. I always use a universal HOAT coolant- these work fine in Volvos.

 

Thanks again Carrots. I grabbed the volvo coolant because I was stopping at the dealer anyway to get the service history and didn't have time to see what else is compatible and what I did read said volvo coolant only. I know the Passat (and likely most VW's) is highly intolerant of mixing non-G12 coolant and didn't want to risk it on the Volvo.

As for the timing belt I believe VW lowered the service interval to 80,000 miles and most places recommend it by 70,000. I'm only at 53,000 miles on a 2003 with the V6, but at 8 years it's getting up there in age. Hoping to push it off till fall when it might be closer to 60k, though at the rate I drive it will probably still be a few thousand miles shy.