My son was in the 40 sitting at a light on a very hot day when apparently the final remaining water must have dribbled out of the radiator and it overheated and stalled. Stupidly, we haven't been keeping an eye on the water, just the oil. An hour later we were able to refill it with hot water and it started right up. We drove it home and it was towed to the shop where they replaced the bad radiator and the upper hose and thermostat. However the tech said the engine still has a problem because the cooling system is being over-pressurized. He was unsure if it was the gasket or a warp but since the expense to find out doesn't pencil here, I tried a couple of bottles of Bar's Leak Head Gasket Fix but it doesn't appear to have helped, or if it has, it's been only marginally.

Others have been enthusiastic about Thermagasket but I haven't gone that far yet. My question here is whether or not these engines typically do warp heads and/or blocks or is the problem usually limited to the gasket?

I'm skeptical about how bad our issue is because we have none of the other "typical" symptoms: It starts right up in the morning and runs as smooth as it used to immediately, there's no white puff out the tailpipe on start, there's no white goo in the oil, and so far as I can tell, I don't believe we have oil in the water either. I'm hoping for some encouragement somewhere as to the likely severity of the damage; I realize you can't eval a problem you haven't physically seen but I've tried to give all the evidence.

We're only driving very short hops for now, as recently when we arrived from a 10 minute/5 mile hop on the freeway and back home, I checked and found the upper hose to be somewhat engorged; I don't believe they swell up at all in routine use, do they? It wasn't "rock hard" as others have described but it was "quite firm".

It's really quite good looking - the sheet metal's perfect, the interior is fair to good, a/c works fine, no smoke, 220k. Final question - any idea what it's worth to a wrecker or a salvage buyer now? I have it on CL for $900 and a guy shot me a $200 offer today which I'm not taking for now.

Ideas?

 

A few thoughts - a head gasket can overpressurize the cooling system but there's a few other things to check out. Does the fan come on properly and does the temp guage read normally? I'd check the ECT (the one in the thermostat housing) and perhaps replace both the ECT and the t-stat. does it leak coolant anywhere or just boil over through the overflow? If no fan action, you may want to sort that out first. You can try doing a exhaust gas/coolant test kit (Autozone carries them, also on eBay) to see if any exhaust HCs are getting into the coolant (standard test of a head gasket failure).

In terms of your car's worth, location, miles, body condition will all factor in. You can price a replacement head by going to car-parts.com (to search for used parts) and ask an indy for the cost to install. The bigger worry about the head is a crack - a machine shop can mill out a certain amount of warpage. I'd look at KBB.COM to see what they say about recent sales for your model/quality/area plus go to autotrader.com to see what the asking price is for similar s40s. That should help you do the math or even decide if you want to take on a DIY project yourself.

 

Thanks for the speedy reply.

Yes, fans seem to run normally. It's not dumping coolant anywhere, and the tstat was replaced at the shop. The temp gauge reads normal, dead 3 o'clock and really doesn't seem to vary up or down at all.

How could the ECT cause overpressure? Boy, if it could, I'd be all over that.

I haven't tried the gas test yet but I guess that's next on the list.

Ever heard of anyone getting joy from Thermaseal?

 

I'd say its a waste of time for your problem. I did some google time - most people who said it worked were trying to fix a coolant leak not trying to keep cylinder pressure out of the cooling system - I don't see how a silicate product could manage that direction. BTW, my comment on the ECT was to suggest it may be possible for the temp sensor to read low and not have the fan come on soon enough - but considering your already swapped the t-stat and your fan comes on, its not a likely cause.

 

Thanks again for your help and google time. I've been over that road as well and I think I agree it doesn't seem likely that a liquid is going to win over a 500 psi cylinder. So it looks like curtains here I guess.

Anyone need a nice V40 body and chassis?

 

I feel Ya. Mines in the shop right now for pressurized coolant, no other symptoms. Probably getting a donor engine. The hg job is a little more than engine swap in man hours. + donor cost. If you have any go fast parts or black interior you could part it out on eBay and get more than that lowball offer. My buddy made a lot locally parting his 02.

 

Surely, if the coolant is getting overpressurised there would be obvious bubbling going on in the coolant reservoir?
There could be an airlock in the coolant system too although less likely if bubbling at the reservoir occurs, being the system's highest point.
Was the correct operate temperature rated thermostat fitted?

 

I have not seen bubbles in the reservoir but I have to agree with you, it seems they must be there. I have to believe the shop put in the correct thermostat as all they do is Volvos and I know the tech to be a very **** guy.

The Bar's HGF didn't work, so I'll be trying the Steel Seal stuff next I guess. It should arrive tomorrow. After reading copious posts, I've decided I'm not really a fan of the particulate liquids, so if SS fails, I guess it's all done.

Thanks,

rw

 

Good luck.

 

I agree with mt6127 with regard to testing the coolant for exhaust gases as then you know for sure if the head gasket is blown. (without question)
I am not a fan on Bars coolant products or the like especially in an all alloy engine.
Water mixed 50/50 with a HOAT type anti freeze is all the engine should have in it.

 

Well, I gave up after running the Bar's HG fix stuff for several days on short trips. I think it >may< have reduced the pressure a bit, just judging by the stiffness of the upper hose after driving, but it still seemed too stiff to me.

So after a final round of soul searching I caved and went for the bottle of Steel Seal, loudly proclaimed as working on You Tube. I spent literally a couple of hours flushing with a hose connected to hot water, until what came out looked drinkable. I installed the SS, did the 5 and 10 mile drives on the freeway as prescribed.

I'm now to the point of wondering if the pressure we see on the coolant is approaching normalcy now. Are these reservoir caps 20 lb.? I seem to remember back in the day that caps were 15 lb.

I'd be curious if someone else might test their 40 upper hose after a drive of at least 10 miles, and then describe to me how tight it is. Or I guess I could post a video of it being squeezed and then you guys who really know these cars could tell me if you think we're close to normal, or close to blowing up... and I realize all of this is maybe academic in the final analysis but we're not in a position to go in on another vehicle. The need is fairly low; my son will be a student at school in downtown Portland but I don't believe we'll be leaving the car on campus, so we may be in the mood to just have this situation play itself out and then maybe be done with the 3rd car for now. Still unknown, I guess.

We have a routine now before taking it out - visually check oil, remove reservoir cap and observe liquid, and then watch temp gauge like a hawk. The gauge actually never wavers from 3 o'clock once it's warmed up.

I guess my question now might be - if we find we can actually make our way here and there without blowing a hose off after say several weeks of this, what's the worst case scenario? I suppose having a heater core hose blow up would be bad... but I'm thinking if we're "close to normal pressure" how bad can it be? I realize maybe we're tempting fate here but it feels so close to being a usable vehicle at this point.

Is it reasonable to believe that the reservoir cap venting at 20 or whatever it is would prevent a catastrophe? We do occasionally hear a tiny hissing sound coming from the cap when we check it after driving, but not every time, either.

Thanks all for your patience reading my rant... I'm always interested in your expert thoughts on this as you might imagine.

rw

 

I don't know where our caps fall into place with the grand scheme of things, but mine is black on my 03.

 

curious if you can get a tool or a shop to measure the pressure?

 

The original tech said he'd be glad to measure it for me if I wanted but I haven't gone back down there as for the time being we're staying off freeways and trying to eval this on short hops.

I am curious though if others wouldn't mind giving the upper hose the squeeze test after a decent drive. On other threads about this problem, I have read posts that describe the upper hose as being "rock hard" which would truly set off the alarm bells with me. Mine isn't rock hard but it is certainly "firm" but still allows some squeeze.

I tested this way on my 97 Accord which is uninjured, and its hose was similarly firm but maybe just a tad less so. I realize much of that may have to do with the original flexibility of each hose, so maybe that's not such a valid test but our 40 has the genuine Volvo hose on it as must of you all must have as well.

?

 

I just ran out to check and our cap is black. So, assuming it opens at 11, wouldn't we be having coolant loss when that occurs? Because there's just a small cushion of air above the liquid in there, and as the coolant heats and expands, to the point of forcing that air cushion out (assuming we're over 11 now), and if we're actually overpressuring the system, I would expect coolant to be issuing from the cap after a hard drive. No?

 

I had lots of hissing out of my cap. And little splatter around my cap, but it wasn't very noticeable amounts lost. Hose was rock hard also. Got a new engine instead of the HG job. It was cheaper given the man hours involved. It's confusing because a lot of sites list the blue lid as compatible.

 

Interesting - I had a black cap but replaced it with another from Tascaparts.com. The one I ordered ended up being the green one (150Kpa) which is what was called for based on the Volvo online catalogue.


EDIT: just went out to the car and took a closer look at my (old) black cap - it is also rated 150KPa (part #30864125).

 

when my 850T overheated due to a failed Tstat a few years back, it completely blew out the green cap causing the boil over. no damage done to the motor as this is a protection mechanism. I happened to be very close (100 yards) to a local shop - they dropped in a new t-stat, coolant and cap and I was on my way. As a practice now I replace my caps every 50K miles or so.

 

We continue to drive short hops 5-10 miles at a time, and I really am starting to think we're seeing a reduction in the upper hose stiffness.

This also occurred to me today: If we do have a breach in the cooling system somewhere, wouldn't you expect then to be able to open the cap and get NO noise of a tiny pressure release, after sitting overnight? We check the level religiously before every morning's startup, and in every case we get a little "phhhhht" of pressure. How could the system retain the slightest pressure if there really was a break in the gasket somewhere?

This also corresponds with the fact that, on cold starts, we have never seen evidence of water in a cylinder.

Thoughts?

 

I'm not convinced that you have leak. I will check "the hardness of my hose" tomorrow and let you know. To me you would have more symptoms than just the one.