Reply
 
Thread Tools Search this Thread Display Modes
 
Old 06-30-2015, 06:32 PM   #1
Ensign
 
Join Date: Jun 2015
Posts: 3
Default Overheated

Huge question here. Our 97 maxum 2100 5.7. It overheated yesterday. We were out on the lake half the day all was fine. Upon running at almost full throttle for five minuets , temp started rising. Got close to 200 degrees. Shut it down , being it was very hot out, didn't help the cool down. Never started it again. Temp got to 175 degrees but decided to paddle to shore. After hours of struggling , we made it.
We've had the boat for years. Never had an issue before.
My questions are;
What could cause this?
What can we do?
If plugged intake water, where to look?
If thermostat , where is it?
Others possiblilities , what?
We live in a rural high desert area. No boat dealers or mechanics within 300 miles.
Any help is greatly appreciated.
__________________

Dlindskog is offline   Reply With Quote
Old 06-30-2015, 06:38 PM   #2
Captain
 
Kevlar7r's Avatar
 
Join Date: Aug 2014
Location: Jacksonville, FL
Posts: 746
Default

When was the last time the impeller was changed? Is it an alpha or bravo outdrive?
__________________

Kevlar7r is offline   Reply With Quote
Old 06-30-2015, 08:23 PM   #3
Admiral
 
Phillbo's Avatar
 
Join Date: Mar 2012
Location: Lake Powell
Posts: 1,250
Default

Impeller could have gone bad. Also you could have picked up a plastic bag on your outdrive and it blocked the inlet (happened to me once).

Run it on the muffs and see if it does it again.

If the impeller is more than a year old, replace it.
Phillbo is offline   Reply With Quote
Old 06-30-2015, 10:05 PM   #4
Admiral
 
mmwjr's Avatar
 
Join Date: Feb 2012
Location: Essex, Maryland
Posts: 7,604
Default

Impeller, t-stat, ... Bag wrapped around water intake.
__________________
1997 2400 SCR
5.7 Vortec / Bravo 2
Mike
mmwjr is offline   Reply With Quote
Old 07-01-2015, 08:15 AM   #5
Lieutenant
 
Skip R Maxum's Avatar
 
Join Date: Jun 2015
Location: California
Posts: 50
Default

If you have not replaced t-stat in awhile, I recommend for general maintenance at least. I recommend buying a mercruiser repair for look up and techniques. Mercruiser Stern Drive Repair Manual 2001-2013 | Seloc 3208

This is something that can be fairly easy to tested and best done by 2 people if you are a novice. I would think someone with decent mechanical experience can test out and repair within a safe environment.

The engine can be raw cooled or a closed system (coolant). I had found searching for "mercruiser 5.7 water flow diagram" that brings up a lot of imagines which you should be able to match.

Being that you have a 2100, I take it that you may have it trailered. That's an advantage for you vs me as my boat is a 3300 and is docked. Perhaps you have muffs for flushing the water? this can help in diagnosing the flow. If impeller, the flow then would be weak and should be inspected for wear and clogs. Replace if needed or if not down in some time.

On the 5.7 carb raw water cooled engine (like mine) the t-stat is on the top front of engine right behind the belt. There should be 4 hoses that go into the t-stat housing. you should be able to trace the flow up from back left of motor to the impeller (bottom left pulley) to the PS honeycomb cooler tube (at back) around right side then back to t-stat housing. The t-stat housing is channel internally for flow to engine water pump and both exhaust manifolds.

When I was looking a 5.7 over, I had taken off the main inlet water hose from t-stat to see the strength of the impeller flow while cranking motor. I had to make sure to stay clear of belts, pulleys, and have a bucket for water flow. Once I did see good flow, I clamped it back on and then went on to test t-stat.

I ran to temp again, used a infrared temperature gun to measure the temp of all hoses and various areas of engine, especially the temp sensor area, manifolds, risers, etc. I was able to see the rise in temp at sensor and housing. Flow then appeared blocked by t-stat. I'd say that if the temp sensor rises to above 165 then the flow should be seen by the t-stat opening (160 rated t-stat I believe) and then the two manifold hoses rise too. The temp gauge / sensor should have fallen. I'd tried tapping lightly on t-stat housing to see if it opened but it had not. I replaced t-stat.

Replacing the t-stat and wanting to do a good job, it will take some time. the repair manual does give some good info. One is that the gasket does have a metal grommet to provide grounding for temp sensor alarm therefore no gasket sealant should be used. I vacuumed out the bolt wells and dried everything out. I brushed the t-stat inlets and painted as needed. Ran back to temp and watch good rise and fall of temp gauge.

these two are not the complete set of items which can cause on overheat, but usually are the two that many can check out on their own. If you are up to tackle some jobs and learn more about the engine, the repair manual is a great way to go.
__________________
- Skip R Maxum
2002 Maxum 3300 SCR
Twin 5.7 Mercs & Bravo IIs
(No Gen, no A/C)
Skip R Maxum is offline   Reply With Quote
Old 07-01-2015, 01:57 PM   #6
Moderator

 
Join Date: Apr 2008
Posts: 4,656
Default

I would not consider running the boat on a hose with muffs as a viable troubleshooting tool . It is possible that enough water pressure can actually pass enough water through the system to keep the engine cool. This would essentially mask a failed impellor. Start and idle the engine in the water and watch the temps.

Impellor's are common and if you cannot remember the last time it was changed, then it NEEDS to be changed.
shrew is offline   Reply With Quote
Old 07-01-2015, 06:39 PM   #7
Ensign
 
Join Date: Jun 2015
Posts: 3
Default

thanks for the much needed advise. In the future , preventative maintenance is a must.
I did read on this forum , there are some who change out the tstat and/or gaskets when Winterizing. Overkill or necessary?
Dlindskog is offline   Reply With Quote
Old 07-01-2015, 10:02 PM   #8
Admiral
 
mmwjr's Avatar
 
Join Date: Feb 2012
Location: Essex, Maryland
Posts: 7,604
Default

Quote:
Originally Posted by Dlindskog View Post
thanks for the much needed advise. In the future , preventative maintenance is a must.
I did read on this forum , there are some who change out the tstat and/or gaskets when Winterizing. Overkill or necessary?
That would be overkill IMO.

Impeller every 2 years.

T-stat and inspect exhaust every 5 years.
__________________
1997 2400 SCR
5.7 Vortec / Bravo 2
Mike
mmwjr is offline   Reply With Quote
Old 07-04-2015, 09:12 PM   #9
Ensign
 
Join Date: Jun 2015
Posts: 3
Default

Thank you for the info. It sure does help. I think a repair Manuel is in order. Knowing more about the engine is important, being one could be stranded.
Replaced the tstat , running water through the muffs , temp got to 180 , with a 160 tstat. But no water came out of the ports. Does this suggest impeller? Or clogged?
Dlindskog is offline   Reply With Quote
Old 07-04-2015, 09:47 PM   #10
Admiral
 
mmwjr's Avatar
 
Join Date: Feb 2012
Location: Essex, Maryland
Posts: 7,604
Default

Most likely the impeller but could be clog as well.

On the Documents tab of this site you will find mercruiser manuals, I believe #24 is the engine one you need for the engine and there is another for drives.
__________________
1997 2400 SCR
5.7 Vortec / Bravo 2
Mike
mmwjr is offline   Reply With Quote
Old 07-04-2015, 09:53 PM   #11
Admiral
 
mmwjr's Avatar
 
Join Date: Feb 2012
Location: Essex, Maryland
Posts: 7,604
Default

You can also Google boatinfo and get any manual you could ever want to see.
__________________
1997 2400 SCR
5.7 Vortec / Bravo 2
Mike
mmwjr is offline   Reply With Quote
Old 07-04-2015, 10:40 PM   #12
Lieutenant
 
Skip R Maxum's Avatar
 
Join Date: Jun 2015
Location: California
Posts: 50
Default

well it is not 200 now... my 5.7s normally shows 170 and 180 on my gauges... seems normally operating range. most other owners show that too....even after the impellers and t stats done for maint. id check things over with infrared temp gun and make sure the critical areas look fine, tstat opens, and be a mindful captain monitoring the helm.and yes replace impeller for maint.
__________________

__________________
- Skip R Maxum
2002 Maxum 3300 SCR
Twin 5.7 Mercs & Bravo IIs
(No Gen, no A/C)
Skip R Maxum is offline   Reply With Quote
Reply

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Powered by vBadvanced CMPS v3.2.3

All times are GMT. The time now is 10:03 PM.


Powered by vBulletin® Version 3.8.8 Beta 4
Copyright ©2000 - 2020, vBulletin Solutions, Inc.