help - blown head gasket ? how to tell?

my wife said she has been having to add about a quart of water a week
to our 79
volvo 240 4 cyl.
also the temp guage goes way high then goes back down.
today I set about trying to find the problem.

- no sign of water leakage that I can find.
- ran a new wire from the sender to the temp guage

took it for a 15 min test drive. it seemed a little gutless, not
running that bad though. then I saw the temp go way up.
pulled over and the water reservoir go right up to the lid.

brought it home and changed the thermostat and swapped the sending
unit from
my 240.

let it rin in the driveway for half an hour or so. it doesent seem
like the engine is getting that hot , but it goes through a cycle
where the fluid level rises in the bottle, builds up some pressure,
and the guage goes up, then the bottle goes way down halfway and the
temp goes back to normal. after 10 mins or so it seems to do the same
thing again.

I did notice that it seems to have a fair ammount of water vapor going
out the exhaust.

I took the plugs out , none looked that bad but number 1 cyl seemed
like the threads wee more coroded , usually I put a tad of oil on the
threads. if there is water in there I think it is number 1.

there is no apparent sign of water in the oil, no froth on the
dipstick or in the valve cover anyway.

I have had some plugs fail on this engine, tiny crack in the
insulator around the electrode , caused rough running .
happened three times in two years.
(bosch plugs)

Do I have a leak causing water to go into number 1 cylinder's
combustion chamber?
anything else I chould check before pulling the head?
I am thinking of having her rent a car so I can have time pull the
head but
I would like to be more sure .

so any advice or tips would be a huge help right now.. !

Thanks very much,
Phil

 

Hey.

Head or head gasket seems to be a pretty good guess.

Reading your post you about covered your easy bases.

I used to run old scrap cars around some old fields, just for the hell of
it. We used to thrash the pants of them and head gaskets were a regular
failing.
Because the head has coolant and oil in them different signs can be seen:

If the gasket has gone between an oil way and the bore blue smoke will be
seen from the exhaust and the plug will get oil fouled. Also a symptom of
worn rings and bores.

If the gasket has gone between an oil way and a water way. You will get
what you described. White deposits on the oil filler cap and in the cam
cover.

If the gasket has gone between a water way and the bore you will get
white smoke out of the exhaust, normally a miss fire usually a more white
than usual spark plug. Plus if you work the throttle with your hand under
the bonnet, with the expansion tank lid off, gun the engine a little then
let go of the cable to allow the motor to return to idle. If you get lots of
bubbles coming up through your expansion tank this would indicate air is
entering the system via some means. If no obvious leaks can be seen I would
elect the head gasket will be at fault. Sorry!

Don't wish to add more to the issue but. If your car has been over heating I
would REALLY get your head checked over for cracks. Hairline cracks are
difficult to see sometimes with the naked eye.

Hope I helped a little!

 

Thanks for the reply. I haven't yet checked for bubbles coming out
from the reservior, but this does sound like what is happening.
guess I had better pull the head.

maybe I should check the compression to see if the valves need work as
well.

phil

 

You should do a leakdown test, or have one done. They set each cylinder to
TDC and pressurize it through the sparkplug hole and then you can listen at
the intake, the exhaust, the oil filler cap, coolant resivoir and the other
sparkplug holes.

 

It could be that there is a failed inline cooling valve in route to the
heater core. Some cars have an inline filter that prevents coolant from
pasing through the heater and out in order to heat up the cabin quicker,
letting heat build in the heater core, then opening to allow the coolant to
cycle.

I'm not sure if the 240 has them, though, but it would be cheaper than
pulling the head on speculation.

 

Most auto parts stores carry a tester than consists of a dual chambered
plastic cylinder than holds a reagent sensitive to exhaust gas. Place the
device over the coolant overflow cap opening following the manufacturer's
instructions run the engine. If there is any exhaust in the cooling
system the reagent will turn from blue to yellow and confirm a head
gasket leak. The tool should be $30-40.

Bob

 

Thanks for all the advice.
To follow up..

I pulled the head, the ring around piston 1 was rusted, and water was
getting into cyl 1. It didn't go into the oil.

I decided to give it the full treatment and have pulled the engine,
had the block rebored, got all new gaskets, seals bearings, a new oil
pump. Had the valves ground, and my local Volvo guy is taking care of
setting up the shims for the head. The crank was pretty nice.
Putting it back together now.
Phil