1991 Volvo 740 Turbo

It appears I have water in my engine. Dip Stick is milky brown and oil cap has a white sludge.

Earlier to day I was getting back pressure in my coolant reservoir and white smoke but car seemed to be running fine.

Last time I tried to start it there was a terrible grinding sound and now we are locked up.

I considered draining and replacing the oil to see if there was any hope, but I guess there is no reason to do that until I find the underlying cause of the water?

Note that I recently replaced the thermostat. It is possible that my son drove it in an overheated condition.

Thanks in advance!

Hi,


You need to remove the engine and check the crankshaft journals. If excessive casting distortion is present, repair will require the replacement of the engine.


Goatman

With overpressure in the cooling system it's probably a blown gasket. Cracks don't let that much pressure in, although they will produce very tiny bubbles in the coolant.
The head has to come off. If you pull the spark plugs you'll find out which cylinder is affected. Once the head is off, rotate the engine around for a while, and oil the bad cylinder to prevent rust, and drain the oil.
The head may be warped. Some good machine shops can re-heat the head on a fixture to straighten it before surfacing. The warp can cause the cam bearing bores to be mis-aligned, so just surfacing the head doesn't help. It has to be straightened first. It's also possible that the head is straight, just a blown gasket. Have it checked though.
Good luck!
Rhys

Thanks Rhys...that actually sounds encouraging. Hopefully I did not run it long enough to do any further damage.

Tell me what I am looking for when I pull the spark plugs?

Gary

The engine may be hydro-locked with a cylinder full of water. When you pull the plugs you'll see. One will be wet from misfiring, and at least be different from the others.
Just yank the head - all else is conjecture until then. I've repaired lots of these engines for gasket failures and cracked heads. All survived to go many miles more.

Gary,


You said that the engine made a horrible grinding sound, and now is ‘‘Locked Up’’. Does the crankshaft turn with the spark plugs removed? If not, you need to check the journals as I suggested.

I am not trying to be negative, I am trying to tell the truth. You likely have severe engine damage.


Goatman

Thanks Goat....I appreciate your input, and I have the same fears that you do - that the damage may be more severe than I can deal with. I have not gotten that far in yet but will update you guys as I do. Perhaps on Sunday if the DFW weather cooperates.

"Last time I tried to start it there was a terrible grinding sound and now we are locked up.

A cylinder could be hydro-locked due to coolant being forced in thru a head gasket breach (by residual coolant pressure) with engine off.

I would pull all 4 plugs then turn the crankshaft over with a 15/16" (24mm) socket on the pulley bolt. If you get thru a rev or two with no binding, a couple of revs with the starter should blow out any remaining coolant in the affected cylinder(s), hopefully reducing fears of major mechanical damage.


--
Bruce Young, '93 940-NA (current), 240s (one V8), 140s, 122s, since '63.

One that is wet with coolant, or just unusually clean (b/c coolant/water mix has "steam-cleaned" everything). If you find this, you will likely be needing a new oxygen sensor as well.

You may not find coolant in the combustion chamber. I did not when the head gasket failed on my 240. Oil and combustion gasses in the coolant, coolant in the oil, and combustion gasses and pressure in the crankcase, but no sign of coolant in the cylinders. All 4 were equally filthy.

Was the overheating situation caused by a stuck thermostat? If the cause is unknown, you need to go thru the cooling system very thoroughly to identify the cause, or you will likely overheat and blow the gasket/warp the head again in short order.

john

Yes, the overheating was the thermostat. I replaced it and thought all was well. I included that info in case it might be important to the current issue.

Today the temp gauge never showed the engine running hot. I just am not sure what might have happened when my son was driving it home with the bad T-Stat.

The cylnder with the leak will have a clean spark plug, or at least it will look different from the rest.

Greg

Ah...thanks guys.

However I replaced all 4 plugs Sunday so i am guessing I wont be able to tell much.