Valve train rattle after water pump failure. Warped head?

[CajunPwnStar]

Had my water pump go out on me the other day on the way home from work. Sending unit wire for the temp gauge was broken off when I hit a limb in a storm and I hadn't gotten around to fixing it, so didn't realize I lost my coolant until I heard the rattle. I immediately pulled over and let it cool down enough to refill it with water. Thank goodness I know the woes of owning a 21 year old truck, so I keep basic tools, water, and common parts in the extra cab. Unfortunately didn't have a water pump. After letting it cool and filling it with a gallon of water, I saw the water coming from the weep hole. It started right up with no hesitation and the valve train rattle went away. When I got in the driveway. I could hear it begin again. Cool, fill, no noise again. I've since replaced the pump and haven't heard the rattle since, no coolant in the oil, etc.

Is there a way to see if the head's warped or would it be best to not chance it and just pull one from the junkyard?

 

[Mark_88]

Do a compression test and try the glove test to see if it is leaking. I've had overheats that didn't actually cause major damage.

We do get fortunate sometimes...

 

[tomw]

This is a cast iron head and block. Unless you have changed things. It will handle overheating without warping the heads in many instances. If it does not consume coolant, and does not over-pressure the cooling system to where the upper radiator hose feels about to burst, then you likely are fine.
If it idles smoothly, (if it did before) then the valves are likely happy enough to get back to business. [If smooth, I would not bother with the compression test until there was symptom of misfire] IOW, do not over worry about this. You likely did nothing to cause permanent damage.
tom

 

[CajunPwnStar]

This is a cast iron head and block. Unless you have changed things. It will handle overheating without warping the heads in many instances. If it does not consume coolant, and does not over-pressure the cooling system to where the upper radiator hose feels about to burst, then you likely are fine.
If it idles smoothly, (if it did before) then the valves are likely happy enough to get back to business. [If smooth, I would not bother with the compression test until there was symptom of misfire] IOW, do not over worry about this. You likely did nothing to cause permanent damage.
tom

Thanks Tom. No misfires or any other noises heard since the water pump replacement. 220k miles and it runs really well and doesn't burn any oil. I was thinking of doing a refresh to it soon with new seals, rings, etc. and was going to just slap on a new head if the overheating was an issue. Since it appears that it didn't hurt anything, that will save me a bit of money.

 

[RonD]

The rattle was from the oil getting to hot and too thin, keep it cool and there should be no problem.


Metal expands when heated, just like most things.

Problem when you over heat an engine is that the head gets very hot and its metal expands more than usual, on the 2.9l and 4.0l heads with a weak spot in the casting this over expansion caused heads to crack, the 4cyl didn't have that problem.
And this over expansion also crushes head gaskets.
Head gasket is between head and block held in place by bolts, so head expands and so does block somewhat, head gasket is caught in the middle
Head expands more than block because coolant leaves the head first when there is a leak, gravity, this also causes a "rubbing" of the head gasket because head is expanding more than block.

Aluminum expands 5 to 7 times more than cast iron, aluminum head engines almost always crush head gasket if over heated.

You could have crushed the head gasket, but it would take a few weeks before breech might show symptoms, it can happen right away, but not always.
It is the soft metal ring on the head gasket around each cylinder that gets crushed.
One little spot doesn't quite recover and the 1,200psi pressure from cylinder firing starts to escape and eat away at the soft metal and then the gasket material, it usually encounters a coolant passage between head and block first, since there are lots of those surrounding each cylinder.
That causes overflow tank to fill up and intermittent over heating as the cylinder gases and pressure flow into the cooling system displacing coolant and causing "air" pockets in the head that momentarily blocks coolant flow in the head.

Depending on where the breech occurs the pressure can push past coolant passage and get to oil passage or valve area drain holes, and then you get the milkshake oil, as coolant passage and oil passage are now connected from the head gasket being breached.


But keep a good thought