[DMCForum] Re: Continuing misadventures of a Volvo/B280F PRV

["cartermartin" <cartermartin@xxxxxxxxx>]

Martin,

Thanks for the reply. It helps a lot and is very informative. The 
cooling system is new:

- y-pipe o-rings (what a pain but they are, in fact sealed)
- heater hoses
- heater control valve
- heater pipe to water pump (next to the y-pipe)
- y-pipe to water pump (large diameter short hose)
- thermostat
- bypass hoses
- waterpump
- upper and lower radiator hoses
- volvo blackstone radiator
- coolant bottle
- radiator cap
- oil cooler hoses (on the volvo the heater pipe  splits off to go 
under the left exhaust manifold to connect to an oil cooler).

I had discounted the milkshake on the filler cap until a 30minute 
highway trip when it did not burn off. 

I guess i'm looking at head gasket time.

You do house calls? ;-{)

Carter
--- In DMCForum@xxxxxxxxxxxxxxx, Martin Gutkowski <martin@xxxx> wrote:
> Hi Carter
> 
> You haven't stated the general condition of your cooling system. 
I've 
> known of a car that would do exactly as you describe - work fine at 
low 
> speerd but overheat on the motorway, and that was down to a blocked 
> radiator.
> 
> However, I would say that if you talk to a mechanic who works on a 
lot 
> of cars (and who has done head gaskets - many shy away from them!) 
> he/she'll undoubtedly have a story of a car which showed up as fine 
in 
> all the tests thrown at it but still wouldn't either run right or 
> overheated etc. Changing the head gasket(s) is usually the last 
thing to 
> think of in moments like that but once done, everything works fine.
> 
> I did a pair of gaskets on a DeLorean last month. The only clue was 
that 
> the coolant kept disappearing when there were no leaks, and it 
would 
> overheat really sporadically. It'd be fine for a hundred miles, 
then 
> overheat on a 6 mile trip. In the DeLorean it's vital to keep a 
healthy 
> level of coolant because once the level drops below the bottle, it 
drops 
> in the pump (most cars will drop in the rad first which is less 
> critical). As soon as the pump loses water - no circulation and 
overheat.
> 
> The filler cap on that car was full of chicken soup but the oil was 
> fine. Buf on cars that sit for a few months and then get driven do 
> accumulate a bit of soup there anyway thanks to condensation. The 
only 
> real evidence once inside was in the heads and on the timing cover. 
> Liner seals almost never fail "on their own" - they usually fail 
due to 
> the liners being lifted when the heads are off, then not being 
cleaned 
> up and replaced. When they fail, you get loads of coolant strait 
into 
> the sump, and you're not getting that.
> 
> Hope this helps
> 
> Martin
> 
> cartermartin wrote:
> 
> > Sorry in advance for the long post.
> >
> > Ok so I think I have gotten to the bottom of my Volvo 
760GLE/B280F-
> > PRV problems or at least nearly to the bottom of it.
> >
> > I have essentially rebuilt my  cooling system. Along the way I did
> > every possible test I could think of for a blown head gasket or
> > cracked head. These include:
> >
> > - Compression test. I got 180-185# on all 6 cyl. The numbers 
might be
> > suspect but felt the fact they are so close together was more
> > important.
> > - Cooling system pressure test. After all the cooling system work 
was
> > done. I pressure tested it at 22# (factory spec for this model) 
for
> > 15-20 minutes. I had very little, if any, leakage.
> > - Tested the cooling system pressure under normal running 
conditions.
> > Pressure was built gradually up to 15-20# or so.
> > - A block leak test. The gizmo that detects exhaust gasses in the
> > coolant by drawing air thru the coolant.
> >
> > Anyway after all of this I still have coolant loss and evidence of
> > high pressure in the system. In this case coolant blown out of the
> > expansion bottle.
> >
> > The only other clue was the chocolate milkshake on the filler cap.
> > When I changed the oil I found no evidence of coolant.  And after 
2
> > negative 'block leak' tests (i.e. no combustion gasses) I finally 
got
> > a positive after a highway run (where btw it urped out a pint or 
so
> > of antifreeze).
> >
> > It appears that under light load, idling or driving around the
> > neighborhood, there is not a problem. This manifests itself at
> > freeway speed when I hear a buzzing sound from time to time that I
> > believe is either the pressure being vented past the radiator cap 
or
> > perhaps even gasses blowing past the head gasket. The latter may 
be a
> > long shot but the sound is coming from the opposite side of the
> > engine from the coolant bottle.
> >
> > At this point my suspicion is either:
> >
> > - small head gasket leak
> > - Cracked head
> > - or maybe a seal for the cylinder liner?
> >
> > I'm still a neophyte on these engines and since it's an old Volvo
> > sedan (as opposed to something more exotic) I should probably walk
> > away. But I feel I want to get to the bottom of all of this. It is
> > also difficult because it's running SOOOOO good.
> >
> > Any thoughts, ideas, or suggestions would be appreciated? Any PRV
> > mechanics in the Atlanta area who can do a head/head gasket, 
please
> > step forward.
> >
> > Oh and for what it's worth I did get the Y-Pipe o-rings sealed up.
> >
> > Carter

---

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