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Vashon_Trawler 09-30-2019 02:25 PM

Steaming again...
 
Hi! A few months ago, I had posted here my saga of my MD2030's white smoke issue, which was largely resolved by servicing my injectors and a water restriction. Well, I am now seeing some steam (not smoke) and elevated engine temperatures. Nothing is odd suggesting a head gasket issue--oil looks great, and the engine holds pressure just fine. The through-hull and fittings are clear, and I've checked for collapsed hoses. The impeller was just replaced and the heat exchanger is also new.

Raw water flows from the seacock to a Perko strainer and then goes through the transmission and up to the impeller. After my last trip, I felt the transmission, and it was hot to the touch; the impeller cover was also very warm to the touch. Gulf temp was 85 degrees, and the exhaust water was very hot.

There "seems" to be enough water exiting the exhaust, but I am wondering if there is a blockage/obstruction at or inside the transmission. The engine/gearbox is 12 years old and has never been "barnacle buster" since I have owned her since 2012 or so. I am going to treat the engine and see what happens!

rslifkin 09-30-2019 02:31 PM

A combination of elevated temperatures and steam definitely sounds like a flow restriction on the raw water side. When you replaced the impeller, did you check for any stray impeller pieces that may have gotten stuck in something down-stream of the pump?

Vashon_Trawler 09-30-2019 02:35 PM

Quote:

Originally Posted by rslifkin (Post 806846)
A combination of elevated temperatures and steam definitely sounds like a flow restriction on the raw water side. When you replaced the impeller, did you check for any stray impeller pieces that may have gotten stuck in something down-stream of the pump?

Thanks. Yes, the impeller is new and I replaced the heat exchanger a few months ago with a brand new Volvo Penta (cost an arm and a leg). The boots were installed carefully and I do not have coolant overflowing suggesting that sea water is not getting in the fresh water side. I've never lost an impeller blade and didn't find any when I replaced the exchanger.

The exhaust riser is "fairly new" (2016 I recall) and I recently opened the various inspection ports to chisel out some carbon--nothing major. I do reach WOT just fine.

Pack Mule 09-30-2019 02:45 PM

Could it be a thermostat sticking? I just reread your post . I don’t think it’s thermostat. A while back my strainer was not sealing off completely and I was getting air bubbles in stainer. I fixed that and also reworked my raw water pump, with new cam, impeller, o ring and new end plate .
The temperatures have improved some but I think I still have a sticking thermostat.

Vashon_Trawler 09-30-2019 03:23 PM

Quote:

Originally Posted by Pack Mule (Post 806850)
Could it be a thermostat sticking? I just reread your post . I don’t think it’s thermostat. A while back my strainer was not sealing off completely and I was getting air bubbles in stainer. I fixed that and also reworked my raw water pump, with new cam, impeller, o ring and new end plate .
The temperatures have improved some, but I think I still have a sticking thermostat.


Hi, Pack. I hope you get your challenge fixed as well. I replaced my thermostat about three years ago with the correct VP part. It was a pain to replace as one must pull the water pump. I went ahead and replaced the water pump while I was there. The raw water pump was replaced around the same time as it was beginning to leak.

Interestingly, the problem coincided with me removing the coolant fed cabin heater and plugging the ports at the engine. The heater must have been dropping the engine temp enough to mask another problem.

I should also add that my engine through-hull is 1/2" NPT with a 3/4" FF barb. To increase water flow, I used a Y splitter to tap into an adjacent through-hull for the A/C. It appeared to help but delayed the steam problem.

Again, it all seems to coincide with the heater removal; I never had this issue before.

I ordered two gallons of Barnacle Buster and will clean out the system this weekend.

C lectric 09-30-2019 08:31 PM

1 Attachment(s)
I have offered my tome below about steaming.
It may not cover everything but it does cover a lot of the sources of steaming.
If there are specific questions later then ask and hopefully they can be answered adequately.

As for the transmission does the unit have a built in cooler or rather does it have an exterior to the gearbox mounted cooler like most drives?

They can become plugged which will cause the gearbox to run hotter, yes, but that can also restrict seawater to the engine cooling.

bayview 09-30-2019 08:43 PM

Just because you worked on lt months ago doesn’t rule out broken impeller, impeller blade or barnacles regrowing in the system.

Lepke 09-30-2019 10:18 PM

When I worked on boats, I fixed many overheat problems others couldn't solve by doing a proper flush of the fresh water side. Often the people before me had installed new pumps, heat exchangers and exhaust elbows and never solved the problem.
Also the anti-rust additives in coolant solutions only lasts so long. Eventually you get a flak rust buildup on the water jackets and in the head water passages. The rust doesn't transfer heat well and you go from normal operation temps to too hot quickly.

Vashon_Trawler 10-01-2019 12:54 PM

1 Attachment(s)
Quote:

Originally Posted by C lectric (Post 806950)
I have offered my tome below about steaming.
It may not cover everything but it does cover a lot of the sources of steaming.
If there are specific questions later then ask and hopefully they can be answered adequately.

As for the transmission does the unit have a built in cooler or rather does it have an exterior to the gearbox mounted cooler like most drives?

They can become plugged which will cause the gearbox to run hotter, yes, but that can also restrict seawater to the engine cooling.


I appreciate the document--very helpful. The transmission cooler is built in. There are two coolant pipes on either side for raw water flow. One coolant pipe is new, but I have not inspected the other. Perhaps a blockage at the cooler. The new impeller was installed Saturday before my trip, and there were no broken fins on the old impeller.

I will report the outcome of my Barnacle Buster treatment. I will also double-check the exhaust elbow inspection ports and run the end of a coat hanger through them. Given the transmission seemed unusually hot and the impeller cover was very warm, I am hoping the issue is a blockage at the transmission cooler.

I will provide a report this weekend!

ronlord 10-01-2019 01:26 PM

Did you actually block the outlet/inlet that leads to the water heater or did you loop them together? If you blocked, you may have restricted some coolant flow. Suggest you try a short piece of hose and loop them together if that was the case.

SeaBreeze 10-01-2019 01:42 PM

Here are a couple of things to consider as well:


Mud/sand in your heat exchanger. If you have operated in shallow water or run your boat at the slip in shallower water, it is easy to stir up the bottom and have it get sucked into the raw water intake. My boat had this when I bought it. I took the end caps off the heat exchanger and shown a strong light through the core tubes. I was shocked to see 20% of the tubes were blocked.


Barnacle growth in your seacock. I had this happen this season. Removed the intake hose at the valve and opened the valve. Water came out but did not gush. I ramrodded the seacock with a wood dowel. I felt the barnacle break off and water came gushing in. Reassemble and enjoy.


Did you burp your cooling system (purge any air out) after working on the waterpump, etc? This can cause your engine to run warmer than designed.



Just thoughts worth looking in to.

Vashon_Trawler 10-01-2019 08:32 PM

1 Attachment(s)
Quote:

Originally Posted by ronlord (Post 807143)
Did you actually block the outlet/inlet that leads to the water heater or did you loop them together? If you blocked, you may have restricted some coolant flow. Suggest you try a short piece of hose and loop them together if that was the case.


Hmmm.... interesting. Yes, I used plugs supplied by Volvo. I kept the hose barbs and could create a loop as you suggested.

Vashon_Trawler 10-01-2019 08:42 PM

Quote:

Originally Posted by SeaBreeze (Post 807146)
Here are a couple of things to consider as well:


Mud/sand in your heat exchanger. If you have operated in shallow water or run your boat at the slip in shallower water, it is easy to stir up the bottom and have it get sucked into the raw water intake. My boat had this when I bought it. I took the end caps off the heat exchanger and shown a strong light through the core tubes. I was shocked to see 20% of the tubes were blocked.

Barnacle growth in your seacock. I had this happen this season. Removed the intake hose at the valve and opened the valve. Water came out but did not gush. I ramrodded the seacock with a wood dowel. I felt the barnacle break off and water came gushing in. Reassemble and enjoy.

Did you burp your cooling system (purge any air out) after working on the waterpump, etc? This can cause your engine to run warmer than designed.

Just thoughts worth looking in to.


Thanks. I checked the seacock and used a small screw driver to clear out a possible blockage. It appeared clear and I had water gushing out. I once had a barnacle growing inside the hose barb on my strainer, which led to an overheating issue. On a related note, I have an annoying scoop strainer that can be a problem keeping clean and clear. My plan is to eventually remove the scoop strainer and replace with a traditional through hull.

I will double check the exchanger as well!

C lectric 10-01-2019 09:22 PM

My gearbox cooler is external but still in the raw water circuit. When I thought I had a different problem I pulled the gear cooler off and found the bottom tubes were blocked, about 20% of the tubes.
I cleaned the whole thing , reassembled and pressure tested and it has been fine since.
I did not see any sign of overheating in the engine but since it is integral in the circuit it would have caused trouble at some point.

Lepke's comment about a flush are valid also. I did mine many years ago and maybe it's time again.

O C Diver 10-01-2019 09:53 PM

Your problem may still be the raw water pump. End plates wear reducing water flow. The bore wears and may be allowing water to by pass the impeller blades. The compression fork may be worn to the point where the flow diminishes.

How many hours are on the water pump from new?

Ted

Pete Meisinger 10-01-2019 10:37 PM

Wow, a lot of good suggestions. Being a Great Lakes cruiser I don't have to deal with barnacles and rust and corrosion are not as big of a deal as you "salties" deal with every day.

But.. one thing really caught my eye ! A half inch through hull to supply cooling water to the engine ? I think mine is a 2 inch hose to the strainer then about an inch or inch and a half to the fresh water pump.

Also my exhaust water is barely warm. My engine runs at 180 degrees but the volume of fresh water through the system is massive, it exhausts cool enough to easily put your hand into the stream.

Just a little restriction could cause the issue of steam.

pete

Vashon_Trawler 10-02-2019 09:20 AM

Quote:

Originally Posted by O C Diver (Post 807267)
Your problem may still be the raw water pump. End plates wear reducing water flow. The bore wears and may be allowing water to by pass the impeller blades. The compression fork may be worn to the point where the flow diminishes.

How many hours are on the water pump from new?

Ted


Hi, OC. The pump has about 75 hours on it since I replaced it. The old pump was definitely leaking. I didn't have any temp issues before replacing it--just water going in the bilge!

Vashon_Trawler 10-02-2019 09:27 AM

Quote:

Originally Posted by Pete Meisinger (Post 807271)
Wow, a lot of good suggestions. Being a Great Lakes cruiser I don't have to deal with barnacles and rust and corrosion are not as big of a deal as you "salties" deal with every day.

But.. one thing really caught my eye ! A half inch through hull to supply cooling water to the engine ? I think mine is a 2 inch hose to the strainer then about an inch or inch and a half to the fresh water pump.

Also my exhaust water is barely warm. My engine runs at 180 degrees but the volume of fresh water through the system is massive, it exhausts cool enough to easily put your hand into the stream.

Just a little restriction could cause the issue of steam.

pete


This is indeed a great source of information, and I will be following through on the advice given here. The MD2030 uses 3/4" hose. After the PO repowered the boat in 2006/7 from an 18HP Perkins, he kept the original 1/2" through-hull and replaced the barb with a 3/4" full flow. Over the weekend, I tapped into another through-hull for the A/C using a Y connector. Interestingly though, I didn't have the steam issue when I originally bought the boat. It all seems to go back when I removed the coolant fed cabin heater.

I am putting my money on a restriction at the transmission cooler but will be checking the other stuff as advised by TF members. I hope to share a positive report this weekend!

Jeff F 10-02-2019 11:15 AM

Lots of good advice here. I'm curious about the actual 'elevated temperature' - is it above spec? That's a small motor to be supplying a heater - maybe it ran cold until you removed the heater loop and is now operating at its design temp. I think you're right in flagging the removal of the heater as a contributing factor in higher operating temps, but if the motor is not overheating you may not have a problem.

kchace 10-02-2019 01:25 PM

To all the very good advice you've received, I would like to add that a restriction or anything that causes low total flow *anywhere* in the system, from the intake through-hull to the mixing elbow can cause overtemp issues. If you don't move enough water through, you won't get the cooling you need.


I didn't see you mention the mixing elbow. If that is clogged with scale or corrosion it can greatly impede the water flow.


Ken


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