89 175 black max running hot

[cyote]

I have a 1989 mercury black max that is running hot under a laod at an idle in a no wake it runs hot but takes a long time and running wide open it does well but at about 3000 rpm it gets hot pretty quick but only when in gear. I have already changed the waterpump the chrome sleve in the water pump and then i thought it was the thermostats so I took the guts out of both of them and that made no difference at all so I knoe I will have to put new thermostats in. Also I have had the poppet valve go out about 2 years ago and changed it but it only ran hot in a no wake when it went it so I feel like it is not it ANY HELP WILL BE APPRECIATED THANKS CYOTE.

 

[gss036]

Re: 89 175 black max running hot

Take another look at your water pump. You did not say that you changed the impeller. Just the SS housing? Make sure you got the slinger on properly and that you are getting the water tube back into the upper end correctly.
Your post is very hard to read and understand without commas and periods.

 

[cyote]

Re: 89 175 black max running hot

Thanks for the reply , and sorry about the run on sentences but I was trying to get a post in between honey dos. I have changed the impeller though and I have a good stream of water coming from it. I was concerned that my temp. guage was not reading correctly, but I checked it out and all is o.k. The part that is confusing is it is mainly running hot a mid range rpms. I checked compression since my last post and every cyl. was at 100. So for now I am still asking for any more help THANKS.

 

[gss036]

Re: 89 175 black max running hot

If you are sure the poppet valve assy is working properly, the next step would be cutting a link out of the poppet spring so that it will open a little sooner. The poppet normally open around 3000 RPM, thus allowing more water flow through the block. You do need the stats installed as the motor will run too cold w/o them. The stats have nothing to do with mid range rpm tempatures, that is conrolled by the poppet valve assy.

 

[cyote]

Re: 89 175 black max running hot

Thanks again for now I am going to change the poppet valve, install 2 new stats and see what weve got. I will let you know something next weekend if all parts are available

 

[cyote]

Re: 89 175 black max running hot

O K upadate on poppet valve install. JUST MY LUCK while installing the poppet valve I removed the guide from the grommet and it fell inside the motor.From what I can tell it is just an exaust vally and I am planning on leaving it inside the motor. Does anyone see ant prob with this, if not it looks like I will have to split the motor. THANKS AGAIN

 

[gss036]

Re: 89 175 black max running hot

Others have had the grommet fall inside. I would try at fishing it out with a piece of wire w/a hook on the end. It may clog up the exhaust system. I think you can get it out w/o splitting the block, that is a little overkill for this situation.

 

[hkeiner]

Re: 89 175 black max running hot

If you are still unable to solve your overheat problem after following the very good advice you already received above, you might consider taking your troubleshooting efforts to the next step....and install a water pressure gauge on your motor. Watching the pressure levels change while the motor is running cool and hot at various speeds will probably tell you a lot about what the problem may be. The following link has more information on this.

http://www.diy-boat.com/index.php?option=com_content&task=view&id=151&Itemid=49

 

[cyote]

Re: 89 175 black max running hot

O.K LATESET AND GREATEST.......................
I change the poppet valve , and tore the gasket on the first attempt , so I bought 2 more. I then changed the poppet , and took the boat to the river again today and still the same. I then removed the cowl and could see water coming from a weep hole in the poppet valve diapram. So I went and bought a big tub like they use to water horses in , so I will not have to keep going to the river, since I am determined to fix this thing myself. I came home and ran the boat in the tub and it would run hot and I could make it do all the same symptoms as on the river. I took the poppet valve back off and could not see anything wrong so I put it back on and overtightened it and broke the outside plate. NOW WE ARE HAVING FUN!!!!!! So my questions are why was the water coming out of the whole on the poppet cover similar to when a auto water pump goes out? And where can I order these parts online since my local dealer does not keep to much in stock , I would like to get new plate for outside, new water deflector and new rubber for inside B/C I do not have these parts new B/C the dealer told me all I needed to change was the spring and the poppet. AGAIN THANKS FOR ALL THE PREVIOUS HELP.

 

[j_martin]

Re: 89 175 black max running hot

O.K LATESET AND GREATEST.......................
I change the poppet valve , and tore the gasket on the first attempt , so I bought 2 more. I then changed the poppet , and took the boat to the river again today and still the same. I then removed the cowl and could see water coming from a weep hole in the poppet valve diapram. So I went and bought a big tub like they use to water horses in , so I will not have to keep going to the river, since I am determined to fix this thing myself. I came home and ran the boat in the tub and it would run hot and I could make it do all the same symptoms as on the river. I took the poppet valve back off and could not see anything wrong so I put it back on and overtightened it and broke the outside plate. NOW WE ARE HAVING FUN!!!!!! So my questions are why was the water coming out of the whole on the poppet cover similar to when a auto water pump goes out? And where can I order these parts online since my local dealer does not keep to much in stock , I would like to get new plate for outside, new water deflector and new rubber for inside B/C I do not have these parts new B/C the dealer told me all I needed to change was the spring and the poppet. AGAIN THANKS FOR ALL THE PREVIOUS HELP.

The diaphragm in the poppit assembly was leaking, and not properly operating the valve. You've probably found the problem. Too bad you inserted another one trying to fix it.

A pressure gauge would have found this problem with the posting of one set of readings. I'd recommend you get one just for good management.

hope it helps
John

 

[gss036]

Re: 89 175 black max running hot

I don't know if MercuryExpress.com is back up and running or not, if not, go to DougRussell.com and order your parts there. There is 2 gaskets (inner/outer) on the covers. You really don't need to get that tight as you found out.
Look at the diagram and make sure you put it back together in the proper order and you will not have leaks.

 

[cyote]

Re: 89 175 black max running hot

Thanks for the site I will be using it tonight and thanks for the help. The reason I did not install the pressure guage is b/c I dont know what the pressures should be anyway, but I guess I could have asked on here. Anyhow back to ordering the new parts and waiting and also the guide that I dropped in the motor previously. Yesterday after running it at the river and breaking and taking it apart a friend came over for me to work on his 4 wheeler and was looking at the motor, well I stuck my finger in to show him where it fell and it (the one I dropped in ) was sitting perfectly behind the new one but when my finger came out it fell again. We ran the boat w/o the poppet in and I plugged both holes with my fingers hoping it would push the old one back up but never did. After this I notice That water comes out of both holes and I was under the understanding that it stayed trapped in one until the poppet opened, w/o the popett in it shot a pretty good stream out of the small one and a steady flow out if the big one...

 

[cyote]

Re: 89 175 black max running hot

O.K. ready to go to the next step. I have installed a new poppet { everything including plates water deflector and all } I then tried the advise of clipping the spring , this did not help. I then put the poppet in with no spring and in 3000 rpm range it did fine , but at an idle it runs hot quick and the pp does not have a steady flow. So now my question is exactly what does the poppet do? And the next is if I put water pressure guage on what am I looking for. THANKS CYOTE

 

[hkeiner]

Re: 89 175 black max running hot

And the next is if I put water pressure gauge on what am I looking for.

As previously mentioned, watching the PSI readings change while the motor is running cool and hot at various speeds will probably tell you a lot about what the problem may be. For reference, a troubleshooting guide from a Mercury shop manual is shown below. If you get PSI readings different than the specs, report back on what you do get at various RPMs and you will get more informed advice (guesses) on what the problem may be. Good luck.

 

[gss036]

Re: 89 175 black max running hot

That is an excellent trouble shooting chart. What it doesn't say is a direct answer to to the above question about the purpose of the poppet. It is there to allow excess water to flow through the exhaust and allow for cooling of the block via, the water passages.

 

[hkeiner]

Re: 89 175 black max running hot

To add to what GSS036 said above, the Mercury shop manual (see below) provides an expanded description of water flow and what the poppets do.

 

[cyote]

Re: 89 175 black max running hot

Thanks to everyone and I am shure I will be back.

 

[Ed R]

Re: 89 175 black max running hot

motor needs, thmostats, poppet,valve,etc. for proper running . Some where in water pump housing, you are sucking air ! It is always over looked. Do not cut, or alter anything! start over! good luck Ed R

 

[cyote]

Re: 89 175 black max running hot

Very imbarressed but I have to be honest after all the help you guys have given me. The problem was in the water pump area , but it was do to my install , I left one of the washers for the top of the water pump housing underneath and it was sucking air. I have not put back together yet but I am positive this time I have found the problem, and thanks again one more time for all the help.