Overheated my Perkins! What damages?

[skwanderer]

Like an idiot I forgot to open the seacocks to the salt water heat exchangers on my twin Perkins 4.236 when I headed out today.

Had only gone about a mile, no greater than 5 knots at any point, when I noticed the temp gauges exceeded the usual 180 degree steady temp. After acouple more minutes, I lifted the engine hatch to be greeted by a big plume of steam. (Not oil fortunately!) I jumped in and opened the seacocks but kept the engines running eventually increased above idle, thinking it would help circulate water quicker. Within a few minutes the temp did come back on both engines to 180 steady as ever. Steam did continue to come out of the exhaust hoses (as well as water as per usual) at the back of the stern

When I got back to the slip about an hour later and inspected the engine room, looks like green coolant sprayed out as I found drops all around. Also found a couple gallons of green coolant/water in the bilge.

So, before I call my mechanic$$$$$$, anyone think I did egregious damage to my engines? I'll check the coolant lines for splits or leaks (as soon as I learn which ones they are. Will check coolant level and oil level. And other ideas to see the health of things?

Many thanks for any thoughts of assistance on assessing the situation.

[waterman46]

I have done the same, but I thought it best to just shut the engine off and let it cool to where I could touch it, then check coolant level and refill as necessary. Sounds like you are lucky you didn't lose too much coolant since you kept running without checking.

[roverhi]

The coolant in the bilge could be condensed coolant vapor. If the engine runs, doesn't overheat, fill the oil sump with coolant, etc. etc. you've probably dodged the bullet. Engines with cast iron heads can take a lot of overheat abuse.

Had some critters crawl in my raw water intake and block it. Boiled most of the coolant out of the Yanmar 3GM30F before I noticed the fog down below. Poured coolant in the engine and nursed the boat back to the slip at idle. That was several years ago and several hundred hours and it's still running fine.

[MBWhite]

As mentioned, if in a similar situation the best thing for the engine is to turn it off if possible and let it cool down by itself.

Otherwise, at this point I'd suggest just topping off your coolant and check the oil and hopefully just call it a lesson learned with no other consequences hopefully. Re-check all the hose clamps in your cooling system in case they have loosened.

The only other thing I would suggest is checking the coolant and the oil before each time you use it the next dozen or so times, but long as your engine sounds normal and you do not have coolant in your oil, or air bubbles in your coolant you should be good to go.

[waterman46]

I forgot to mention, you should check the rubber impellors in your raw water pumps. Running those for a long time, dry, may cause damage. If they look good, be sure the vanes are still flexible and haven't been hardened by overheating.

[RaymondR]

If you did not get the engines hot enough to seize them I doubt that you did a great deal of damage. Cooked seals tend to harden so inspect for oil leaks.


If you have water cooled exhausts hoses and plastic waterfall devices I would go over them very carefully particularly the short run between the exhaust manifold outlet and the waterfall device. Squeeze them for soft or hard spots..

[Lepke]

Perkins are pretty tough. I have one on a generator that's 40 years old. Like the others said go over your water fittings, hoses, and impeller. If the impeller got hot it could make the paddles hard and brittle. If they break off, they could plug your heat exchanger.

[skwanderer]

Thanks so much fior all the thoughtful replies! Much appreciated. Will take all advice and added maintenance checks and steps to heart.

[Triton]

Hi im a marine engineer had this call out often. Advise the following 1. Oil and filter change. High temp has depleted oil additives, and possibly glazed bearing shells / Lacquers 2. Send in oil and filter sample for analysis to detect High lead in oil Pb. or copper, aluminium and coolant 3. Replace raw water pump impeller. check water lock / mufflers, exhaust hose, header /expansion tank, coolant hose / clamps for split damage. Master oil pressure check idle and full must be in spec. coolant pressure checks to determine heat exchange seals and leaks. Half interval oil / filter change and resample analysis.
Cheers
Tony

[skwanderer]

Will do. Thanks!

[Sandero]

One of the key checks when you fire up the engine is to observe the exhaust which should be spitting/spilling sea water... If you don't have the normal amount of water spurting out of your exhaust... you are heading for an overheating or at minimal a too high run temp.... which will creep up higher and higher because of inadequate cooling.

Lack of healthy exhaust water splash-spurt-water ejection is a sign of one or several of the following which need to be fixed pronto:

close sea cock on the engine cooling water
blockage in the line anywhere from the sea cock to the exhaust thru hull
broken impeller (perhaps causing reduced flow from blockage lodged in the hoses or engine. Could be clocked strainer.
breach in the cooling water plumbing leaking (spraying) water (into the bilge)
faulty thermostat, loose hose of hose clamp....
possibly vacuum block in the plumbing

[sainted]

The biggest concern is the exhaust system. Raw water is used to cool the exhaust, and the exhaust system is NOT designed to cope with hot exhaust gases. There is a good chance that the water lift mufflers and rubber exhaust hoses were damaged. With the engines running at the slip go over the exhaust system inch by inch from the exhaust manifold to the stern checking for water and exhaust leaks, burned spots, melted spots, and so on.

You should also change both raw water impellers, change the oil, and top up the coolant as other have suggested.

I also agree that internal damage to the engines is unlikely. You'd have to run them hard and hot for quite a while to do that.

BTW, you did the right thing by continuing to run the engines after you opened the seacocks. Continuing to circulate coolant while the raw water sucked heat out of the coolant kept the temperatures even throughout the engine. Uneven temperatures is what causes cracks in metals. That's why you never pour coolant into an overheated engine without it running.

[hamburking]

Originally Posted by sainted

The biggest concern is the exhaust system. Raw water is used to cool the exhaust, and the exhaust system is NOT designed to cope with hot exhaust gases.

The previous owner of my Volvo 2002 did exactly that, melted the whole exhaust. So when I bought the boat, it had a brand new exhaust, from block to thru hull. However, there was no apparent engine damage, even 6 years later...running great.

Its been said before, and its worth saying again. Start the engine, and check for water over the stern. Then check sporadically. When your crew start mocking you for checking the exhaust too often...you've got it right.

[skwanderer]

All excellent additions to my newly forming departure checklist.

Sounds like I should get my mech back in for that cooling system service. Not confident yet in my DIY abilities.

One thing additionally that I observed is that the oil pressure used to run consistently at 60, but at the overheating and after it dropped to ~50. Though I haven't checked fliud levels yet this morning, any ideas in the cause of drop in oil pressure?

[seasick]

Keep an eye out for symptoms of head gasket damage due to head warping.

The first thing to fail is usually those cheap plastic muffler/mixing boxes. Hopefully you don't have those.