This cannot be good /already off to a bad start. (see pic)

Post by **Southbay850** » 02 Jan 2013, 18:52

Well just picked up a 90 740t and was getting it ready for a minor tune up so it would be good to smog. The car sat for over a year but ran fine. So I was doing what i call a wake up process.n ( oil, coolant, hoses, belts, plugs, ect.) So I started her up no problem and was letting all the fluids do their thing before checking them. Well to my surprise not in a good way I found this. See pic attached. I dont think that it is a good thing. As a matter of fact I first thought Head gasket however there are no other signs that come with a blown head gasket like oil in coolant steam out of tail pipe over heating coolant and what ever else I didnt mention. I had seen this on my 850 before but i fixed it with oil change and maybe seafom. Now I am not familliar with the 740 turbo but I do know a bit about the 850- t and its turbo plumbing. These two are way different as i was comparing them side by side. The thing that I was confused about on the 740 was how the coolant hose is hooked up strait to the turbo and there are a bunch of hoses that go back and fourth to the engine and intercooler or radiator. Now here is some things that happend today as I was trying to trouble shoot why it didnt want to start after it was starting for me all day long. I could only get it to start after removing the cap on the coolant overflow tank. It kicked over just after it belched orange colored coolant from open tank. When I went to see what happend I saw a mist rising out of overflow tank and it smelled like partially burnt gas. All this may be unrelated but I know someone can tell me what I have sitting in my driveway with the name volvo on the rear hatch. Is it something worth fixing or just call pick n pull?

volvoholic · Post by **volvoholic** » 08 Jan 2013, 21:38

You have a bad Head Gasket! The motor was most likely overheated at some point. The HG is easy on these cars, even if you have never done one, this is the one to start on...Hopefully the head is not cracked, but at any rate you will have to get it to a machine shop to make sure it's not warped. This would be your biggest cost, the HG set is cheap. Or you can source another head... But get rid of that oil because this a lot of water in it and it will rust the bottom end if you wait too long....

Post by **Southbay850** » 12 Jan 2013, 23:17

I changed the oil and filter and so far it has not come back. I will definitely look at the hg. Thanks.

Post by **JDS60R** » 12 Jan 2013, 23:34

Its normal for the oil cap residue to look like that "if" the engine hasn't been driven in a while. Wipe it off and see if it comes back. If not then don't worry. If it does come back, Check the coolant for hydrocarbons . Then you will know if your head gasket is gone.

Post by **Southbay850** » 13 Jan 2013, 19:13

When you say hydrocarbons in coolant would that be a gas smell in the coolant tank? I keep smelling a gas smell in there and it seems to have a lot of pressure in it.

lummert · Post by **lummert** » 13 Jan 2013, 21:29

Bingo! The smell is most likely escaping compression gases leaking into the coolant. Pressure testing the coolant system would confirm this.