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Two Questions

H

hippie

Regular Contributor
"Hi everyone, I have two quest

"Hi everyone, I have two questions that I hope you men can answer. 1- I'm still overheating. It's a 350 Mercruiser, 1988 with an Alpha-1 outdrive. It is not a closed system but uses raw water. I replaced the Thermostat with a new one and still have the same problem. When changing the thermostat I didn't tighten the two bolts in the thermostat housing enough and water was spraying everywhere. It had good pressure so I don't think the circulating pump is bad (besides it doesn't leak or "chatter). Also, because it is getting water from the impeller (which was changed over the winter)the water inlets above the prop shouldn't be clogged with barnacles or growth. What can it be? 2- I fixed the charging problem but today I hooked up my tachometer and the voltmeter dropped from 14 volts to 13 volts. I don't think the tachometer should draw that much voltage. You men are the experts so please give me a few ideas. Thank you, Bob"
 
"Bob, overheating how? On land

"Bob, overheating how? On land, in the water,At idle, midrange, hi-speed.
Making sure you have a good water supply, remove the inlet hose at the thermostat, get a bucket, have someone start engine and get to 1500 rpm, should flow at least a gallon in 15 seconds.
1-incorrect assembly of impeller
2-copper connecting tube short or corroded hole
3-rubber gasket missing from pump upper body or at the water pocket cover
4- transom water hose kinked or collapsed internally
5- water inlet clamp at thansom (inside) crushing hose connection
6- power steering cooled clogged
7 -thermostat housing clogged internally
8- risers plugged up from corrosion"
 
What occurs before and during

What occurs before and during the overheating? What temp. does it go to?
 
"BT and GUY,
It overheats in

"BT and GUY,
It overheats in the boat slip. I will start the engine and at idle (750 RPMs) the temperature just begins to climb. A slow steady climb and in about 5 minutes it is up to 210* and I'll shut it down because it is getting to hot. It used to be if I increased the RPMs to about 1200 the temp gauge would come back down but now it just keeps climbing. The thermostat that Mercruiser recomends is 160*, which is what I put in. So if the thermostat starts to open at 160* by the time it gets to 180* it should hold at that temperature. I cleaned the thermostat housing when I put the new thermostat in and replaced a metal fitting to the rear of the housing that connects a rubber hose to the housing with a radiator clamp. BT, now that you mention it, I have been going through a lot of power steering fluid lately. I checked for leaks but cannot find any. How do I check the power steering cooler to see if it is clogged or leaking steering fluid into the water cooling system. Thank you both for your help and please continue to give me advice. Thank you, Bob"
 
If you have a sheen of oil in

If you have a sheen of oil in the water around the stern of your boat that would be a good indictaion of oil getting into your cooling system. And yes the Thermostat being installed backwards was one of my thoughts as well.
 
"Guy, In your diagram #6 shows

"Guy, In your diagram #6 shows as a sleeve. I looked at this when I put the thermostat in and did not see any sleeve. Is it possible it was there but not loose so I didn't see it? Also, my thermostat only fit in one way due to the bevel and groove in the thermostat housing where a coark gasket and rubber "O" ring went on top of the thermostat. Neither of these (the gasket and O ring) seemed to fit in tight and seemed out of place at the time. Is this because the sleeve (#6) is missing? Sorry to put you men to this much trouble. Thank you, Bob"
 
No need to apologize Bob. The

No need to apologize Bob. The T'stat copper pellet goes in toward the engine and not the cover assy. Your model does not use an "O" ring; look at the pic. by part #. You need the sleeve; it helps keep the T'stat from seizing and directs hot water.

I had a dealer part sales clerk try to tell me I needed the "O" ring; she was looking at the wrong diagram. When she was told she was wrong all heqq broke loose and talked to me like I was an idiot. I went down the street and bought a complete Merc. T'stat kit. They told me not to use the "O" ring on my model. LOL
 
"ok, I'll get the sleeve a

"ok, I'll get the sleeve and take out the "O" ring. I will look at the thermostat and double check to make certain it is installed properly. Thank you again, Bob"
 
Also doesn't the cork gask

Also doesn't the cork gasket fit around the thermostat ? (sorry been a year since I last touched one)
 
"I have to go to the boat tomm

"I have to go to the boat tommorrow and see exactly which cooling system I have. I was looking and it shows 3 types of systems. If you look at design 1, mine has a lower part like it has but yet mine has a top with nylon balls and springs such as design 2. I will take pics to determine what design it is. Thanks again, Bob"
 
"Well here is where I stand. T

"Well here is where I stand. The thermostat was inside the housing correctly (the copper piece with a spring around was down inside the housing with the other part facing up). I then checked the cooling design yesterday and tried to put the plastic sleeve in the housing but it did not fit because it was too long. I took it back and bought the brass sleeve which was to big in diameter also but the length was correct. I spent 6 hrs trying to figure it all out but can't. I came home and spent another 4 hrs on this computer trying to find a diagram of my cooling system. On the bright side I found the engine serial number and outdrive number. Two other numbers make no sense at all. So now I have no idea what to do! Thanks again, Bob"
 
Get a Dremel and use a coarse

Get a Dremel and use a coarse sanding drum to remove the scale buildup. Finish up w/a fine sanding drum to polish it. Best tool I ever bought.
 
If you continue not to be able

If you continue not to be able to fix your problem maybe you should try speaking to a women because some of us just happen to know a thing or two about boats!
ps: Guy when you were speaking to the sales clerk did you happen to give HER the right s/n of your engine because any good parts person male or female if given the correct info should have no problem telling you what you are going to need.
 
""...did you happen to giv

""...did you happen to give HER the right s/n of your engine..."

I gave her the year, HP and model of the engine. She let me look at her diagram on the computer and I told her that was not the right one. She insisted it was. The boat was sitting in her shop. I said my Merc. shop manual shows a cork gasket is used. She ignored me and again said it uses an "O" ring. Using the brass sleeve w/the "O" ring the cap doesn't fit flush w/o torqing down on the bolts.

I don't begrudge any shop making a reasonable profit one bit. This shop sells almost everything it can over the counter piecemeal at rediculous prices. I wanted 5 grease fitting caps; she wanted $3.99 each. I bought 8 delivered for $3.75. I couldn't buy a Merc. thermostat kit; all by the piece. Not one cork gasket in stock."
 
"My system has 7 hoses coming

"My system has 7 hoses coming off the housing. I'm trying to find a system like that in the Mercruiser diagrams. I will keep you all posted. Many Thanks, Bob"
 
"ok, after talking to three di

"ok, after talking to three different Mercruiser dealers and getting three different answers my daughter (a WOMAN) called the Mercruiser main office. SHE ascertained the part numbers we need. I will install and keep you all posted. Thanks again, Bob}}"
 
"Sandkicker, Thank you very mu

"Sandkicker, Thank you very much. I have spent untold hours looking for that setup. Nowhere do they show a housing with 7 outlets/inlets. I'll put it together tommorrow and see what happens. Thanks to all of you men, Bob"
 
I put the therm. and new sleev

I put the therm. and new sleeve and gaskets in yesterday. It solved the problem and the temp. holds just below 160*. Thanks to everyone that helped with advice. Bob
 
"I took the boat out today and

"I took the boat out today and it ran hot!!! Coming in to port I noticed the temp. gauage at 240* Not good. Where do I go from here? Also the engine would not rev above 1400 RPMs, and I had a tough time starting it. It is a Thunderbolt IV ignition system and it seems that the timing is off. I know you ground the white/purple wire but where is this wire located. Mine are white/green and white/red coming off the distributer. Thanks again, Bob"
 
"Back to square one. If you h

"Back to square one. If you have a large tub fill it w/water and a running hose and lower the OD into it. Pull the hose supplying water to the T'stat hsg. from the OD and start the engine while you see if the hose/water will fill a bucket in 15-30 seconds. Yes? OD impeller and water passage is OK. If not, pull the hose off inside the gimbal and see if the opening thru the gimbal is narrowed.

Pull the rotor off the dist. and look for rust on the optic sensor. If it's rusted replace it. Check and clean the wire connections to the module; it controls the spark and may be dead.

Check and seet the timing.

Pull the elbows and get them cleaned at a radiator shop.

Tests for Thunderbolt Ignition:

W/ignition key on AND BILGE WELL VENTILATED OF GAS FUMES!!!

Check the kill switch first!

#1 - Connect your voltmeter neg. lead to the engine ground and pos. lead to the white/red wire terminal at the dist. It should read 12 volts.

#2 - If 12 volts are present, remove the coil spark wire from the distributor and connect it to a spark gap tester to ground. Remove the white/green lead from the dist. terminal. Turn the ign. key to on and strike the white/green lead to ground. If there is spark, replace the ignition sensor in the dist.

#3 - If there is no spark, substitute a new coil and repeat test #2. Now if you get spark, install a new coil. NO SPARK, replace ign. amp.

#4 - In #2, if there is No voltage present, disconnect the white/red wire and check it again for 12 volts. If 12 volts is present, replace the ignition sensor inside the dist. cap. If no 12 volts present w/it disconnected--ignition amplifier is shot and must be replaced."
 
"Guy, I was at the boat yester

"Guy, I was at the boat yesterday and performed the tests which you gave me. They showed I needed a module so I went to the shop and they wanted $300.00 for just the module. I said no and returned to where my boat is kept and the men there said to get whatever I might need from a boat they are scraping. It contains two engines just like mine. I took the module from one and put it in my boat and it solved all ignition problems. Starts right up!. Now the cooling system is still not working. I removed all hoses on the port side and all have water circulating through them. The fitting at the gimbal is not corroded as none are. The boat has been in the water since April and hasn't moved from the slip. I scraped the barnacles and crud off the water inlets in the OD but everyone says the growth gets inside the OD but then why do I have water coming in from that hose? Sat. morning we are going to pull the boat and pressure wash the hull and OD to see if it helps. If you have any other suggestions please let me know. Many thanks, Bob"
 
Bob:

Go back and get the ot

Bob:

Go back and get the other module for a spare. Barnacles can grow inside the OD especially it the boat sits for long periods. Remove the two water inlets and look inside for some barnacle growth. How old are the manifolds and elbows? They don't last long in saltwater. They are probably blocked w/corrosion. If that is what you find then either have them cleaned and pressure checked or replace them with OEM parts. Stay away from GLM parts. Try eBay for OEM parts. I bought a new set a few years ago cheap.
 
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