How could both engines be running hot? 320DA

[scooper321]

I bought my 320DA about this time last year. On the survey report, it's lists the temp of the engines as 165 and 170. I don't recall when those where measured - that is, at idle or after the trial.

I've noticed that the engines appear to run hot. When I first power up, they jump quickly to about 170 each. Then, with very little load, they move up to between 170 and 220 on the gauges. Call it 190 or 200. There they stay, even as I cruise for a couple hours. Are these temps too hot?

From what I've learned and heard about this engines (FWC 5.7L Merc Horizon 350 MPI) these temps seem hot. I checked to coolant in the overflow and added a little (neither was alarmingly low) and also in the heat exchanger. In both engines' exchangers, the fluid was clean, no signs of debris. I ran them both and notice the the port engine overflow did rise (as I'd expect) as the engine warned. I didn't see as much movement in the stbd engine's overflow. In fact, I did notice a couple air bubbles in the hose from the stbd engine hear exchanger to the overflow. But at least I know they aren't low on coolant.

I thought maybe the thermostats were bad, but it seems odd that both would be bad at the same time?

I asked my mechanic, who thought at this time of year, in warmer water, the bottom probably has growth on it, blocking either the raw water intakes or outflows. I guess that would make more sense, but I think I've had this problem most of the season. When I first launched the spring, there was difficulty getting water exhausted from the engines as the idiots at my marina appear to have bottom painted over my sea water intakes and exhausts. They were opens up them, but I suppose they may not be 100% clear. And add in growth and maybe that is the problem. i have an appointment to haul out and power wash to bottom on Monday. And I'll examine the raw water ins and outs then too. But is there anything else glaringly obvious that I should be checking? Has anyone else seen this in these engines? Or, could it just be out of whack gauges (but both at the same time?)? I do plan on getting an IR thermometer next week to seek out temp hot spots in the system, too.

Any insight would be appreciated.

 

[SeaAyeOwe]

When were your raw water impellers last replaced?

 

[Lazy Daze]

Temps are definitely too high. Not the point where damage is being done, but too high none the less. Check strainers. Check impellers and wear plates. Plan on replacing at least the impellers if it's been at least a year, as long as you're in there. Still might need to replace them even if they were replaced at the end of last season - especially seeing that you're in the Bay and could be running shallow at times, picking up sand. You could do the raw water pump test, if you wanted to. If good flow there, then maybe the heat exchangers are somewhat clogged.

 

[scooper321]

Thanks!

I had the impellers replaced when I winterized last fall. So I'd like to think they are ok. But it's good advice to check. And I was thinking the strainers too. I tried to look at them yesterday but couldn't get the damn sea cocks closed! Taking a pipe with me next time to slip over their handles...

How do you do a raw water pump test?


Sent from my iPhone using Tapatalk

 

[Pseudomind]

Do you have strainers or possibly even old water hoses for your water intake? I know of more than one instance where boats do not have strainers or old hoses and when the hoses are under pressure they collapse in, similar to pinching a water hose off, decreasing water flow to the engine and overheating.

 

[scooper321]

Do you have strainers or possibly even old water hoses for your water intake? I know of more than one instance where boats do not have strainers or old hoses and when the hoses are under pressure they collapse in, similar to pinching a water hose off, decreasing water flow to the engine and overheating.

Well, the hoses look pretty good, as far as I can see. And yes, I have strainers, or at least I believe I do. Ha ha. I have heard of more than one instance where someone has opened the strainer cover only to find out the strainer screens are missing! Those are something that I want to check, as they could be clogging the intake, too. But I couldn't get either seacock closed when I was down there on Friday, so I couldn't open them up to see. I don't expect they are too dirty, because my mechanic cleaned them when he winterized the boat last fall. But of course, God knows what I picked up on them this season. Based on the warm weather and water temperatures we've been having it's possible that there are jellyfish in there!

 

[CJ Martin]

If the screens are missing, it sees more likely your heat exchanger is full of goo from cooked sea nettles.

 

[scooper321]

Well, I don't think that's the case. I was just mentioning it because I read it elsewhere.


Sent from my iPhone using Tapatalk

 

[scooper321]

So I got a short haul today. Bottom power washed. While there was some build up, the intakes weren't blocked. On the positive side, I did find a piece of rope wrapped around my prop. Ok, that's not the positive. The positive was that it was just spinning there, not tangled in the shaft or prop. Glad I got it off. And further good news: I picked up a knot or two on my cruise speed at the same RPM. But the engines still run hot. Next up, I have to check the strainers. Hoping I can get my face close enough to see in the glass window. Otherwise I have to pull them. After that, I'll check thermostats and then look for clogs.

 

[Lazy Daze]

You don't have to "pull" the strainers. The lid comes off for easy access.

 

[scooper321]

You don't have to "pull" the strainers. The lid comes off for easy access.

Well, mine are mounted vertically so I basically do have to pull them. But I know what you're saying. What I meant was I need to pull them out and inspect them and clean them. And the problem isn't taking the lid off, it's getting access to, and turning off the sea cocks that feed them.

 

[Lazy Daze]

Well, mine are mounted vertically so I basically do have to pull them. But I know what you're saying. What I meant was I need to pull them out and inspect them and clean them. And the problem isn't taking the lid off, it's getting access to, and turning off the sea cocks that feed them.

Yup... I understand that all too well! :smt001

 

[Vince_nj1]

I have cleaned my sea strainers without closing the sea cocks. A little water will come in, but not a big deal.

 

[ENstig8or]

I have cleaned my sea strainers without closing the sea cocks. A little water will come in, but not a big deal.

I do close the sea cocks while I clean the strainers but I do open them back up for a bit before replacing the strainers to let any trapped gunk out. I also take a toilet brush to them before closing them up.

 

[rondds]

Exercise all sea cocks as often as possible (mains, genset, air condx). If they seize it's a pain to get them moving again, and it's dangerous should a hose let go and you need to shut them down in a hurry.

 

[scooper321]

Well, progress is slow but after a trip to the HW store for PVC and some contortionist moves that remind me I need to lose my belly, I was able to close the sea cocks. They weren't stuck, just stiff. Got the strainer screens out and there was a little residue in each that looked like rubber or bark or bottom paint. But very little. Absolutely no blockage going on there. The water remaining in the strainer bodies was clean. Well, as clean as brackish will be, but you get my point. Doesn't look like any blockage or impeller explosion. And I figured this because i DO get raw water flow out the stern when idling (through the exhaust bypass).

So other than massive blockages in the heat exchangers, about the only thing I haven't checked yet is the very first thing my Dad would have told me to check in an old car: the thermostats. I just can't believe they both would have died at the same time. But I'll check them as soon as I can figure out how to drain the coolant without making a mess in the bilge. If that doesn't turn out to be it, maybe I'll clean the terminals to the temp gauges on the dash and then conclude I really don't have a problem after all.


Sent from my iPhone using Tapatalk

 

[dpmulvey]

Where are you measuring the temps from? Gauges are notorious for being wrong. DAMHIK!!! If you don't have one, I would suggest purchasing an infrared temp gun from Harbor Freight. They are about $10. Both my engines were running in spec

 

[scooper321]

Where are you measuring the temps from? Gauges are notorious for being wrong. DAMHIK!!! If you don't have one, I would suggest purchasing an infrared temp gun from Harbor Freight. They are about $10. Both my engines were running in spec

Good question. I'm just judging off the dash gauges. And I agree with you about their inaccuracy. What else would explain both engines malfunctioning exactly the same? I bought the HF IR temp gun last weekend and plan to use it tomorrow. Where, exactly, would I take readings? The block? The exhaust manifold? Somewhere else?

 

[Pseudomind]

I hope you find the issue.

I would doubt your gauges have gone that bad since the survey with readings of 165- 170 to 190-200?

I was basing my comments from a friend who has a Carver with two Mercruiser High Output 496's and the issue he had was overheating while underway. His problem was two fold, one his boat did not have strainers, ( he does now) and two the inside of his hoses would collapse when he was underway, similar to pinching a garden hose off to stop water flow. When he would idle down all looked normal hose wise from the outside when looking at the hoses. Their rigidity was gone, throttle up, more pressure in the hoses would pinch them off.

 

[rondds]

Steve, shoot the thermostat housing. That's where the sensor is usually located. You can shoot elbows too, which should be no more than around 120* (you should be able to lay your hands on them and not get scalded). Also, shoot your heat exchanger, since that's where the cooling really happens.

Curious to see what you come up with. Good luck.