No Exhaust Discharge
Date: July 19, 2000
From: Mike Harwood mbharwood@compuserve.com
I need some pointers - I have Yamnar 2QM20 on our E32. Having realised that the zincs needed replacement I have used this opportunity to replace the thermostat and to clean out the sea water strainer, I checked the impeller and that seems to be OK.
On replacing all pipes and firing up the engine I have no water coming through the exhaust, she just over heats. In the past I always have a flow of water coming through from the moment the engine was fired up.
I have checked the pipes for air leaks and cannot find any. I do not know how to "bleed" the system to remove any air blocks. There is a hot water tank that uses the bypass water before flowing into the exhaust elbow manifold.
Any suggestions for fellow Yamnar owners would be a great help. Stuck at the dock.
Date: July 20, 2000
From: Tom Berardinelli coolchange@mediaone.net
Mike
I have the same boat and engine,also had the same problem. Everything checked O.K., but no water was coming out the exhaust. What I did was take the raw water intake hose off and put it in a bucket of water. Before I put the hose in the bucket, I started a siphon by pouring water into the intake hose. As soon as water started to be drawn in I put the hose in the bucket until water was pumped up and out steady. Try and keep the water from emptying by putting a thumb on the hose opening, then, with engine off, put and clamp hose onto raw water intake without losing the vacuum in the hose. Now start engine and watch exhaust outflow. This might need to be done more than once,till there is no air left in cooling system. It works for me every spring! GOOD LUCK
Date: July 20, 2000
From: Pete Doddato lapdog@olsusa.com
Hi Mike,
I recently did what you did to your engine except for the thermostat. I know this sounds dumb ..... but the seacock is open right? If it is you should have water up to the water pump as it is just about at the water line. The pump should push water through the new pipes ok so an air lock isn't likely. Maybe take the cover off the water pump and see if the impeller is turning.....maybe its stripped on the shaft. I change my impeller anually regardless of how it looks. You are getting water up to the strainer above the seacock right......if not maybe you have a frozen seacock. If it is the old gate value type you can't tell if they are opening or not. I replaced all of mine with the lever type. Can't think of anything else. Sometimes it is the very simplest of things that stump us though. Can the thermostat be put in upside down? Don't know if that's possible.
Date: July 20, 2000
From: Bill Lezotte wlezotte@indiana.edu
Mike,
I recently had a similar problem. I found that the exhaust mixing elbow had gotten plugged with all the decomposed zinc stuff. I was able to clear it with a screwdriver. I also found that the zinc had also plugged the entire aft side of the 2QM20s head. By crawling in behind it you can remove four bolts that hold a plate that holds the zinc and again use a screwdriver to clear it.
Another way to try to find the plug is to start at the water pump. Remove the hose to the water intake and blow. You should hear bubbles under the hull. (One time I had the seacock closed, Oops). Then reconnect and move to the next hose. The hose that goes from the pump to the block intake. Remove the hose from the block side and turn over the engine. If water comes out then your ready for the next. Just above the pump to block hose is a block to manifold hose. Remove the hose from the manifold side and turn over the engine. You should get water the also. Continue the same process to the manifold to water heater hose and the heater to mixing elbow hose. If all hoses produce water then remove the exhaust hose from the mixing elbow and blow. (yes, it tastes really really bad) You should hear bubbling in the muffler tank and you may hear water out the stern of the boat.
If my writing is too difficult to read or understand I can scan the flow diagram from my Yanmar manual so that you can have a visual reference.
To answer one of your questions, there is no "bleeding" required on the cooling water system. If there is any air in the lines it will leave very quickly once the engine starts.
Good luck to you and please let me know if I can help any further.
Date: July 20, 2000
From: Albert Augustine ABig2guy@aol.com
HI MIKE: I have the same 2qm20 in my 76 endvr. when my engine overheated i assumed sea strainer, NOT.. checked thru hull for blockage, NOT.. removed impeller cover and impeller appeared good, NOT.. here the brass insert in the impeller had spun and broke its bond with the neoprene of the impeller body. if that doesn't fix it then try bypassing the hot water heater. i assume your engine is sea water cooled and the heater original. Possibly some crud dislodged and is restricting the flow.
Date: July 20, 2000
From: Kevin D. Coon kkcoon@worldnet.att.net
Hi!
Is the gate valve stripped and not openning? Is there an air leak in the strainer (that is usually the problem with mine.) You can hook a garden hose up to the input of the strainer (cut off the garden hose end fitting first and hose clamp it on). Turn on the water , look for leaks- start the engine look for leaks. This may show up leaks that suck air during normal operation.
Sometimes big hunks of crud from the zincs come loose and clog up the water jacket, but I'll bet it's sucking air somewhere.
Date: July 20, 2000
From: Tom Gilbert TGil95746@aol.com
Mike.... I can suspect a simple solution...... I did this once!!! Is the thermostat installed backward? If it is, it would not open in time for the water to pass through it. The engine would quite possibly overheat before the thermostat would recognize hot water flowing to it, and not open since the hot water is on the wrong side for the sensors. The engine runs way too cool for the heat xchanger to be of any value on my E32, but it still is a part of the outflow process....... good luckkkk...
Date: July 25, 2000
From: Jay Call jaycall@mediaone.net
I recently had the same problem on the same engine after cleaning the raw water strainer. The problem was, the old seal in the lid of the strainer was so hard and cracked, I didn't even realize there was one in there! Net result was that when I reassembled everything, there was an airleak at the strainer, and--well, no water flow. Anyway, I took it apart again, scraped out the old, hardened rubber seal, cleaned the brass lid, then made a new circular seal to cover the inside of the lid. Reassembled everything, and she worked like a champ. By the by, did you get the zincs out of the backend of the engine head without twisting the bolts off?
Date: July 25, 2000
From: Mike Harwood mbharwood@compuserve.com
Paul, I thought this would help the Forum page.
Thank you for all your support, without it I would have given up and got someone to do it for me - saved me lots of $$$$.
Conclusion was the exhaust elbow had blocked. Solution - clean the elbow with a wire brush, old toothbrush, a piece of wire coat hanger and a household dish cleaner.
Solved with - Purchased - Gaskets, Zincs, Thermostat
Used - Bucket, socket set, hose, wire brush, dish cleaner, wire coat hanger, screwdriver.
Done at the dock with assistance from the family.
Solution found by elimination -
Clean the seawater strainer - it is amazing what gets through the seawater intake. Replace and fill with water.
- Remove the pipe on the intake of the impeller water pump - blow in it! You should hear bubbles coming through the seawater intake - then a yucky part, suck to be sure the seawater flows both ways. Connect the pipe back to the pump. If there is no bubbles or the water will not flow check the seacock. Have been recommended to prime the pipe once re-connected. Remove the top of the seawater strainer and top up with water, until it over flows, then tighten up the top.
- Remove the next pipe - it flows from the water pump into the engine block. With the pipe directed to a bucket turn the engine on - water should flow - if it does the problem is NOT the impeller - if there is no water flowing inspect the impeller, the rubber impeller may have parted from the housing - replace. Air may be seeping in from the gasket, reseal with new gasket - be careful of the brass screws, the heads strip too easily. It has been suggested that the gasket may be too thick and a paper-thin gasket is needed. The seal needs to be perfect.
- The next pipe to test is the intake to the thermostat - repeat the process of removing the pipe and starting the engine and hoping the water flows, into the bucket.
- Next pipe - depends if you have a hot water tank - if you do there are both intake and out flow pipes to test before reaching the exhaust elbow. This will complete the testing of the by-pass water flow from intake to exhaust.
- My problem was the intake of the by-pass water flow into the exhaust elbow. It was blocked. There are four bolts that mount the elbow to the exhaust manifold, first remove the large exhaust pipe; the intake of the by-pass water pipe will still be removed. The bolts will probably need a lot of WD40 before they budge. Once removed clean the elbow with a wire brush, old toothbrush, a piece of wire coat hanger and a household dish cleaner and you should be able to clear the blockage in the elbow.
- On replacing the elbow and all the pipes, prior to firing up the engine again ensure all seals are tight. Having tightened up all parts fill the engine with water, via the top, at the cylinder head - it takes about 1.5 liters.
- During the initial investigation I took the opportunity to replace the three zincs and the thermostat. Remember that the zincs at the front of the engine have a copper washer but the back zinc, located on the rectangular inspection plate has a gasket that may not be offered when buying replacement zincs! It is amazing what you can do with a breakfast cereal packet! The thermostat is easy to replace, remember the gasket too.
- If you have had to take the whole water system apart, take the opportunity to use fresh water to flush out the housing. Zinc, mud, gasket bits, carbon deposits and general crud will restrict the flow of the exhaust system.
- Firing up the engine and seeing water come out the exhaust is one of life's little pleasures - unknown till you see it does not flow!
Date: August 20, 2002
From: Andre D'Elena Andre_D'Elena@pgatourhq.com
Excuse my ignorance but what are these zincs you speak of. I purchased a '79 E32 about 6 months ago and it has a Yanmar 2QM with just such a problem. This is the first time though in about 6 months of very ocassional use (I've been on the hard working on the hull - blister job, let's not talk about that now.) I started the engine using fresh water from a bucket about once a month and this is the first time it hasn't sucked lots of water. Wouldn't you know, the freakin' same day I'm going back in!! Anyway, I'll start going through the system as suggested but I'd still like to know about the zincs.
ps - I've already checked the impeller, raw water strainer and seacock and all clear.
