Alpha 1 and air in the system

"Last season I had an issue wi

"Last season I had an issue with my port engine. It seemed that when at the dock the engine would reach temp ( 143 deg.) and then the temp gauge will fall off to zero. I checked all the wiring, switched port and starbord gauges, enen changed the circ pump on the port engine. During the winter I changed the water pump base upper, impeller andthe copper tube and assembly that cools the upper part of the drive as well as feeds the water to the engine. My question is, can the hose in the bell housing cause air to enter the system ?"

"Joe:

If the gauge reaches

"Joe:

If the gauge reaches 143 F. and then falls to 0 F. it's a thermal problem. It sounds like the sender is breaking down OR the wire connector is dirty or loose and continuity is lost when it reaches 144 F. Check and clean the wire and the sender elec. stud. If it continues, replace the sender or swap it w/the other engine's sender."

"I replaced the sender, and th

"I replaced the sender, and the temp did exactly the same thing. I placed a clear plastic tube from the oil cooler to the thermostat housing and there was air voids within the hose, also the temp gauge fell to zero during this time. My mech stated that it was a problem below the impeller., however, can the water tube within the bell housing cause this same problem?"

The hose from the oil cooler t

The hose from the oil cooler to the OD or the outer hose from the OD LU to the Bell hsg.? I guess if there is a crack in the outer hose it may allow air in the system as water leaks out.

With the engine off hook up a garden hose and ear muffs to the LU and then pinch off the inside hose before the oil cooler w/a needle nose channel locks just enough to cut off water flow. Have someone turn the water on high as you try to see if water is leaking out of the outer hose.

If the pump impeller is working then there should not be air above the impeller since it is submerged. Remove the water inlet covers and look for debris just for the sake of it. Back flush the LU from the oil cooler and see if debris comes out.

"One thing was not mentioned i

"One thing was not mentioned in the data given... Is there any indication the engine is actually running hot or improperly that would be attributed to overheating? Or does it run well, maybe not at any given temperature on the guage, but have good smooth performance.. Particullay after it has run long enough to be overheated if adequate cooling water is not being circulated?

Trying to cipher between electrical signal and mechanical failure.

Did you replace thermostat or test its opening temperature? If thermostat has failed in open position or responding non-proportional to actual engine cooling water temperature, the engine could be running well but below normal temperature. Most guages I have owned do not really indicate engine temperatures below about 90 to 100 degrees, and needle lays at bottom position, not really zero. If thermostat is not working correctly, you could be running at slightly above actual water temperature, which this time of year is lower than my guage will report."

"Guy, the hose within the bell

"Guy, the hose within the bell housing is the one I am concerned about. The port engine does overheat! mosltly runs at 180, this is not normal, the starboard engine runs at exactly 143( the thermostat temp range.) The port thermostat was changed, my real concern is that the lower unit on the alpha 1 gen 1 may be worped? (I hope not.) I also shot the top of the thermostat housing with an infra red gun, temp was normal (143-150),I removed the thermostat housing after noticing that there were air voids and noticed that ther wasn"t any water within in the well of the housing. ( there was water in the block, I can empty the engine through the pet valves on the bottom of the block.) I looked at the hose within the bell housing and did not notice any holes, or kinks.Iwas also told that I should run the engine in a plastic garbage can and see if this occurs again I guess that this simulates being at the dock.The only other thing I can think of is the hose connection from within the bell housing and the transum assembly. If this connector has a hole in it then that may be the issue? My next try will be to place a garden hose on the bell housing, remove the hose from the thermostat housing block that opening asnd see if there are any leaks.Otherwise I am at a loss! Thanks again for all the encouraging advice."

"What engine and year is this

"What engine and year is this one? Is the T'stat hsg. separate from the intake man. or does the T'stat drop into the intake man.? What have you done concerning the OD lower unit?

"I looked at the hose within the bell housing and did not notice any holes, or kinks"

Did you look w/a flashlight while the engine was running?"

180 degree's doesn't s

180 degree's doesn't sound like it is overheating to me.

"The engine is a 1990 5.7 Merc

"The engine is a 1990 5.7 Merc. The T- stat sits on top of the intake, and it has the spring and relief beads within the host.( they work.) I will try running the engine and looking into the bell housing to see if there are any leaks."

"Joe:

You need to take the

"Joe:

You need to take the LU off and inspect it. There is a copper water tube that has a rubber seal atop of it that is installed in the base of the upper half of the OD. That could be your problem child if the tube doesn't seal properly. While there replace the entire water impeller assy., both upper and lower hsg. halves. You'll be able to see the top seal."

"I ran into this same problem

"I ran into this same problem once.In my case I replaced the plastic(copper in some cases) fitting where the hoses go thru the transom,bellows,you name it, and water hose.Depending on where the drive was positioned,it let more water thru then other positions.Was ok moving, but idling along the temp would cruise up, and at times drop off as you mentioned.Not enough water.When installing that hose,I learned you need to put a slight twist on that hose as our merc mechanic showed me.Solved that problem for me after a re-do.Hope that is of any help.Do not want to see you lose an engine....Todd"

"Hi Tod, I haven't looked

"Hi Tod, I haven't looked at the tube that runs from the bell housing into the transom assembly. I am interested in the comment" slight twist " on the hose. Are you saying that the hose gets a kink into it if is not placed correctly in the bell housing?. I tried to look at the hose and I cant see much. Some merc tech said that I have to move the steering wheel to the lest( drives move toward the right.) so that I can see up within the bell housing. If all fails I will just change the hose in the bell housing, however I have been told that I can't just change the hose, I have to remove the bellows and shift cable bellows to install the hose. Can the hose be installed without removing all the bellows?"

"You'd have to be part mon

"You'd have to be part monkey to change that hose without removing the drive leg and the leg bellhousing.

Removing the bellhousing is not that bad a job if you have the right swivel pin tool. While doing the hose it would be adviseable to change out all the bellows, and if at all in doubt about the lower shift cable, replace it too since you are that far into it.

Rod"

Can you remove the bell housin

Can you remove the bell housing pull it foward and change the hose and water tube in the transom assembly with out removing the bellows and all the other complecated stuff in there?

"Joe,
What I found out was

"Joe,
What I found out was by just putting the hose in, it looked great, but did not really work.The little twist I was taught,simply made the hose work freely so to speak, no matter where the drive is lifted to.Keep in mind you are not to have the engine running with the drives up all the way.
What I had to do was un-hinge the bell housing,release one side of the exhaust bellow,remove water hose at drive end.Re-install while checking hose as you go to see that it works ok up and down.Not very dificult...just take your time....Todd"

The little twist is important

The little twist is important to assure that the water hose does not kink when the drive is in the down position. There is slack in the down position because the hose is just long enough to make the connections with the drive in the full up position.

Hope you are planning to remove the drive leg when you do this? If you unhinge the bellhousing you can pull it back and twist it side to side such that you can get to the hose fitting on the transom assembly. Note that there is one certain position for the hose clamp. Put it back exactly as you find the original.

Rod

"At this point the drive is no

"At this point the drive is not installed. I am from Long Island, we haven't gotten any great weather so far. My Merc tech says that ithis is a complecated job. I will read about it at the Mercstuff.com"

"Good idea.
You should know w

"Good idea.
You should know what you are getting into.
Most people would change all the bellows at the same time as they are not expensive to buy, and it would be a real PITA if you had to do it all again in a year to change them.

Rod"

"Rod and I are together on thi

"Rod and I are together on this on.In our opinion it is possible for you to do it.However it can be a bit frustrating if you never did this before.In some cases it is better to pay and let someone that knows do it, but pay close attention so next time you understand what is happening.This is your choice.We will help the best way we can by your replies.Sure others will join in as well.Want to see ya enjoy boating this summer....Todd"