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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

Reply to
mrhuntnpeck
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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!

Reply to
Artful Dodger

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

Reply to
mrhuntnpeck

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.

Reply to
James Sweet

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.

Reply to
Jeff Lesperance

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 -- The goal when driving is to miss the maximum number of objects.

Reply to
volvowrench

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

Reply to
mrhuntnpeck

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