Closed Cooling System on Port Engine Running Hot(ter)

[tpenfield]

Make sure to check Doug Russell in Worcester, they have their best pricing on their ebay store, but will match it in person. Not that close to the cape,but they have oem stuff priced well. and they are pro's.

Thanks for the tip, NH Guy . . . 'Woosta' is too far a drive for me for today. I am just hopeful I can get the part within about a 15 mile drive. :noidea:

However, if I get to the point of dropping in a new engine Doug Russell would be high on the list

 

[alldodge]

I did a basic test on my workbench this evening using air pressure, and they seem to regulate low and one of them I can hear leaking.

What about checking your old ones this way?

 

[tpenfield]

What about checking your old ones this way?

I was definitely thinking of doing that, but I'd like to have spare regulators in hand when I do that.


For now I have the original regulators back in the boat and the engines are working.

I literally called 15 dealers in the area and none of them had the part. I also called the West Marine to see if they had the Sierra equivalent, none of the stores have them either. I called NAPA auto parts and sure enough they have one out in Fresno California

So my game plan for today was to run the compression test and take a look inside the cylinders with my borescope if possible. I ran the engine up to temperature 165? And let it cool down a bit then pulled the spark plugs. To my amazement the plugs now look more normal than they did before.

Here are my compression test numbers

1-128
3-117
5-111
7-116

2-123
4-118
6-122
8-124

They seem a little bit low to me but I can't exactly recall what I was getting before. I'm going to take a look inside the cylinders just to see if I see anything of concern with the valves.

Of course, the seller on eBay is giving me a lot of back and forth questions about the parts that I want to return. Why wouldn't he

 

[alldodge]

Those numbers are getting low, should closer to 150
Throttle full open?

 

[tpenfield]

Those numbers are getting low, should closer to 150
Throttle full open?

Doh. no . . . forgot . . . so may be add 10 psi :noidea:

 

[alldodge]

Ya know with a bit low compression (even 135) I would expect it to run a tad bit rich not lean

 

[tpenfield]

What surprised me was the spark plugs looked fine. Much better than when I checked them a couple weeks ago.

I inspected the valves with my inspection camera and they looked OK - square edges and I did not see any signs of then burning away.

So, I put everything back together. The port engine at idle goes to 165 as it did before. The starboard engine goes to 150.

 

[tpenfield]

So, sorry for so many text posts with no pictures . . .

Here are a few pictures

The spark plugs . . . these actually looked OK versus what they looked like a few weeks ago. . .


They look a lot better (I think)


Here are a few shot of the inspection camera looking at the valves . . .







Intake on the left . . . exhaust on the right.




Anyway. I am going to order genuine Mercruiser fuel regulators (one one foe each engine) and swap them out.

 

[achris]

Swap the regulators across the engines.

 

[alldodge]

They look good

 

[tpenfield]

I ordered 2 new regulators from a Mercruiser parts warehouse, so I think I will just go with the new one for the port engine and keep the other as spare in case the starboard engine has issues later on.

Any thoughts on the condition of the valves . . . even though the pictures are a little fuzzy ?

We have a big crew this weekend to go out on the boat .. I think I will have 11-12 people . . . so we shall see how it goes with a heavy load.

 

[achris]

I would also be concerned that the temp goes to 165 at idle (no load). Would tend to indicate the problem is very much in the cooling system itself. I would only expect a lean condition to cause overheat under load. And as it doesn't get any hotter under load, I would be even more suspicious of the temperature regulation and reporting systems. Am I making sense, or do I sound upside down?

 

[alldodge]

Agree, the cooling at idle at 165 is an issue. The HE is doing its job, and maybe be doing better because the flow rate is restricted as HT mentioned

 

[achris]

Ted, did you pull the engine circ pump and check it?

 

[tpenfield]

Ted, did you pull the engine circ pump and check it?

I have not but can do that at some point

 

[achris]

Agree, the cooling at idle at 165 is an issue. The HE is doing its job, and maybe be doing better because the flow rate is restricted as HT mentioned

Agree. The longer cooldown time as Ted pointed out may be an indicator of a reduced flow rate. Now, whether that reduced flow rate is in the HE or the engine block is still to be determined. My preference would be to rig up a low pressure gauge and/or a flow meter in the line between the raw water pump and the HE. Any increased pressure would be indicative of a restriction. If the flow and pressure are good, move to finding a reason for a reduced flow rate in the engiine itself. It's only logical Mr Spock.

I believe we have come full circle, but found a few other problems needing attention along the way (and learned a heII of a lot in the process). :thumb:
So far we have covered cooling (engine running warmer than 'normal'), fuel (low rail pressure), and electrical (Diacom errors on Port engine)... Yep, covered about all of it.

Chris......

 

[HT32BSX115]

If the flow and pressure are good, move to finding a reason for a reduced flow rate in the engiine itself. It's only logical Mr Spock.

One easy way to check the flow rate through the entire raw water system, would be to disconnect the raw water connections to both risers, use some hose to connect them to a plastic "T" (1.5" size or so fittings) and measure the raw water discharge that would go out the risers.

Allow that water to fill a 5 gallon bucket and time it at say 1000 RPM for both engines. (the risers shouldn't get hot enough in 30 seconds or so but I wouldn't run it much longer.

If you want to run it longer, and you're in a slip with water for washdowns, connect the "dock" hose to the risers and run water to them so you can idle a little longer without overheating them and the rubber parts.

If you have no water at the slip, get a small trashpump or other small water pump to supply water for the risers long enough to keep them from getting hot.

It will be somewhat work intensive, but if the port engine (raw) flow is considerably LESS than the starboard engine at 1000 RPM, you'll narrow down other places to look.

 

[achris]

One easy way to check the flow rate through the entire raw water system, would be to disconnect the raw water connections to both risers, use some hose to connect them to a plastic "T" (1.5" size or so fittings) and measure the raw water discharge that would go out the risers.

Allow that water to fill a 5 gallon bucket and time it at say 1000 RPM for both engines. (the risers shouldn't get hot enough in 30 seconds or so but I wouldn't run it much longer.

If you want to run it longer, and you're in a slip with water for washdowns, connect the "dock" hose to the risers and run water to them so you can idle a little longer without overheating them and the rubber parts.

If you have no water at the slip, get a small trashpump or other small water pump to supply water for the risers long enough to keep them from getting hot.

It will be somewhat work intensive, but if the port engine (raw) flow is considerably LESS than the starboard engine at 1000 RPM, you'll narrow down other places to look.

:thumb: Love it. Simple and very indicative. I wouldn't bother teeing the outlet hoses together, just plug one and measure the volume over time from the other.

 

[HT32BSX115]

just plug one and measure the volume over time from the other.

That's even simpler. !!

 

[tpenfield]

Nice summation guys :thumb:

I think the internal (closed side) flow rate has yet to be determined. At one point I had looked to see if I could find some relatively inexpensive flow rate indicators . . . sort of like a visual pinwheel indicator . . . to get a visual on the open side water flow. I didn't really find anything that was right sized for the application . . . unless I wanted to spend a bit of green.

If I can find something, then maybe I could also monitor the closed side flow rate as well.

I did at one point disconnect the open side hose that leads to the exhaust elbows to get a quick visual on the flow of raw water from the HE. Looked fine. . .

One thing that I did along the way was to run a very intense (50/50 mix) of injector cleaner and fuel through the port engine. That may have given the injectors a bit of new life, re-gaining some of their efficiency, and perhaps making the fuel mixture a bit richer.

The only significant clues so far have been the lean burn looking spark plugs (which now seem to be fine ) and the lower pressure at the fuel rail. Yet to be determined is if the recirculating pump has some issues.

We will be using the boat this weekend and then not for a couple of weeks, as we will be vacationing in the Western USA - Grand Canyon, Yosemite, Arches, etc. I should have the parts by then (seem to be special order since they were used only for 1-2 years back in the 1996-97 time frame). So, probably not until the end of August will I have an update.

Game plan would be:

Replace fuel pressure regulator
Remove/inspect recirc. pump.