Engine overheated

I was exploring the lake this weekend and went up on of the arms which got quite shallow. After turning around and heading back to open water at idle speeds i noticed my check engine light was on and the engine temp was around 220. I figures something was blocking the inlet so I switched the engine off opened the cover. Confirmed there was still water in the water strained and it was clear of debris, then went for a swim to see if something was blocking the inlet and it was clear.

I figure i'd try start the engine again and see. The temp came down which I feel confirm that something was stuck on the through hull and turning the engine off released it.

I guess I just had a couple questions on the incident.

1. What temps would start to do real damage to an engine? Do I have anything to worry about for hitting 220?

2. What should I have done in that situation? Would it be a good idea to turn the engine off then on to see if that clears the through hull and brings the temp down.

3. What else should I check if the engine starts to overheat?

First time out, we hit a sandbar and fried the RWP housing I'm guessing from the sand. At the time, i was told to just "open her up" to get water going through it. It didn't help since the RWP was no longer drawing water. We hit 220 as well and thankfully there was no damage to the exhaust pipes, t-stat, heads, or ex manifolds. Unfortunately we did blow a hole in the side of the muffler. New RWP, repaired muffler and the boat has run at 160 ever since. I would bet you caught it early enough that it didn't do any damage especially since it cooled back down.

MrMcD wrote: if no water is there the gauge actually reads cooler than the block

How can the engine be cooler without water than with? If this were the case the water would have to be hotter than the block. I think you've got it backwards.

MrMcD wrote: Ever lose a lower hose on a car or truck?

No but I've lost a significant amount of coolant leaving the temp sensor dry.

MrMcD wrote: The engine block will be much hotter than your gauge is reading by the time the temp sender picks up the temp.

No. Once revved up and the circulation pump filled the block (immersing the sender) with what coolant was left in the radiator the temp READING dropped immediately (to that of the block with coolant)

Reaction time is one thing but a dry engine is not cooler than a wet one. If this was the case your "coolant" is heating up your engine...

Hollywood

I'm not too busy this afternoon, I think I might go out and overheat an engine and give you and Mr McD some more info to disagree on. I'm not quite sure how I want to go about it though. Maybe a boat, maybe the plow truck

Then again maybe I'll just go for a boat ride.

You might say it all "boils" down to the thermal conductivity of air vs water.

I hate to say it, but you guys are pretty much saying the same thing in different words.

Time for that boat ride now

KenO

Hmmm,   Kinda goes back to my discussion last winter on installing a water pressure sender hooked to a piezo buzzer. Pressure drops and the buzzer goes off well before the temps skyrocket. Everything could be hidden out of site.   Going in my boat for sure.

We're not saying the same thing.

If your block has some water in it, but not enough to immerse the sender (located at 12 o'clock) your actual engine temp is lower than what the gauge is going to show.

I am still trying to figure out how to block the water inlet without damaging all the running gear.

I'm just happy the boat returned to normal on its own! Too many sad stories here of blown head gaskets, warped heads, melted exhaust hoses, blown mufflers, and worse.

Oh of course. My waverunner hates eel grass with a passion. Or maybe it likes it and I hate it. It sure clogs up the water intake on that thing!

Dreaming wrote: Hollywood wrote: We're not saying the same thing. If your block has some water in it, but not enough to immerse the sender (located at 12 o'clock) your actual engine temp is lower than what the gauge is going to show. my experience says otherwise, but I am not sure of the reason.     I had a car with a very small head gasket leak that would start to run funny when it was low on water and started to heat up, however, the temp gauge would not indicate a hot condition.   The temp gauge did work accurately when there was sufficient water in the system. Any chance that in a boat with no input water, the exhaust would backfill the water jacket? seems like this would be the logical reverse path if the inlet water source was plugged.

Well back from the boat ride and another "lets call it a hands on demonstration"

Just like dreaming says when that sender is in the air because the water level is low,it's reading a lower temp than the water and the engine.

You lose enough water and the engine overheats while you're looking at a temperature gauge that reads lower than normal If you happen to have the heater on, that nice warm air that was blowing out is now luke warm at best since you're below the level where the heater supply taps off the engine too.

With Hollywood's logic you'd have hotter air in this case

I have a friend who runs a junkyard and this afternoon I stopped by and we took a car that was going to the crusher with an engine that still ran (on maybe half of it's cylinders), drained all the coolant out and filled it about half full with plain ole water, disabled the fan left the cap off and drove it till the engine overheated.

The temp gauge lagged way below normal, it read barely on scale and there was plenty of 212 degree steam blowing out of the radiator. The heater was blowing air that was not much warmer than the outside air.

I have an old plow truck that tells me when it's time to add coolant. The heater starts blowing cool air and the temp gauge has dropped down quite a bit from normal. This is just like what dreaming described from experience. Fill it up and everything is back to normal

There is plenty of heat transfer, fluid flow and thermodynamic logic at play but it all comes down to the ability of air to transfer heat as compared with water's ability to do the same. Way more than there is room for here.

So.........Hollywood I have to agree, you're right, you're not thinking like MrMcD but you should be even though most of this thread doesn't really pertain to Blamey's original problem.

According to those who know me, like say my wife or my junkyard buddy or some others, motivated would be the wrong word.

Out of my mind might fit better. Lots of other words would work too.

And........it's always easier to understand when you can actually do things and see the results and pass them on.

I think Hollywood is still laughing about the "turn the engine over backwards to check the compression" experiment.

KenO

JoeinNY wrote: Too many variables to make a decisive call here... but I would be hard pressed to make a ruling based on any car engine experiences/scenarios

I agree but I too love Kens "out of his mind" experimentations!

Just to dip back into the original question for a minute.

Check your strainer: For debris, for presence of the gasket and for tightness.

Keep an eye on your temp gauge on future outings. It could be the thermostat as mentioned above. It's also come up in the past that the hub of some impellers can bust loose from the rest of the impeller and freewheel. This causes intermittent stoppage of the impeller.