Still heating up...

TXTripper

Seaman Apprentice
Joined
Jun 28, 2004
Messages
30
Ok, so my '86 Bayliner capri w a Volvo penta aq125/270 outdrive is still heating up when run over 2700RPM's. I keep a careful eye on it and back it off to cool down once it reaches about 190-200. Runs at a hair below 180 normally. If I put it in neutral I can run it about 3000RPMs and the temp comes back to normal very quickly. Interesting, NEVER overheats in Neutral or with muffs on no matter how hard its run. Also it runs great under 2700 RPMs with no problems all day. <br /> Would having 100% coolant in it rather than a 50/50 mixture have anything to do with it? I believe this is what the mechanic put in at seasons beginning and I haven't changed it. Its also got a new impeller, new bellows, and all oil is freshly changed. still fishing for the answer. Thanks-
 

Blk-n-Blu

Master Chief Petty Officer
Joined
May 12, 2004
Messages
821
Re: Still heating up...

TX, here is an interesting article on mixing anti freeze and water. Hope it helps. The article is from another site and the authors name has been excluded.<br />There are some misconceptions in the service trade Regarding, the amount of antifreeze and water for protection in winter weather and sub-zero climates.<br /><br />A mix of water and antifreeze EXCEEDING the 50\50 ratio (say 70\30) increases the freeze point protection down to -72 degrees F., but at the same time, it will reduce the cooling efficiency of the system. And, when the weather warms, such a 70\30 mix could cause the Engine to overheat.<br />A blend of 50\50 (water and antifreeze) brings protection down to -34 degrees F.<br />On the other hand, a 100 percent antifreeze solution (no water mixed in) has a freezing point of only 10 degrees F. above ZERO, it could turn to pure slush when outdoor temperatures drop lower than that.<br />One more bit of caution, Today's electronic engine control systems use a<br />TEMPERATURE SENSOR to send varying voltage strength signals to the on-board computer. With an improper mixture of antifreeze and water, the boiling point of the coolant will be changed. This simply means that the signals sent by the temperature sensor may be altered and cause a change in the calibration of the computer's output programmed control signals. A higher level of emissions is one result. Equally as important, if coolant in the system is below the correct "fill" level, the temperature sensor also will send out false signals and upset computer output commands.<br />The result of the low coolant level (especially electronically controlled engines) can also cause such problems as poor drive-ability, stalling, hesitation, poor fuel economy, and an increase in exhaust emission levels. Advise your customers of the important need for an annual cooling system inspection. Make them aware of how critical it is to maintain coolant at the proper level (and mix) all year! They'll never realize all of this unless you present the information at every face-to-face opportunity.<br /><br />Adding Fresh Anti-freeze to Old Anti-freeze<br /><br />You should be aware that adding new anti-freeze to very old anti-freeze can cause particulate matter ,suspended in the old anti-freeze, to precipitate out, and settle in areas of the block and heat exchangers. This particulate matter contains mostly rust, dirt, and the old anti-freeze itself, that has started to coagulate. This process can occur with relatively new anti-freeze that has been subjected to overheat or was originally mixed with high mineral content water. The bottom line is that it is safer to recommend anti-freeze replacement to your customers on a regular basis. Boats especially left in storage for long times should have their anti-freeze changed more often to reduce this type of settling.
 

Chris1956

Supreme Mariner
Joined
Mar 25, 2004
Messages
28,102
Re: Still heating up...

TX Tripper, Is it possible the raw water intake is partially clogged? Mine get barnacles which restrict water flow and cause overheating at higher speed.
 

TXTripper

Seaman Apprentice
Joined
Jun 28, 2004
Messages
30
Re: Still heating up...

BLk-n-Blu, thank you for that article, I think I will flush the entire system and put a 50/50 mix in there. Being in southern Texas, we don't freeze much, but I did notice some of the particles that were described. <br />Chris1956, I guess that there could be something in the intake, but it has only been in Freshwater. Barnacles aren't an issue. I am trying everything else before disassembling the whole intake waterway. Thank you for the input though, its definately a possibility. <br />Thanks!
 

dsorrell

Cadet
Joined
Dec 21, 2003
Messages
28
Re: Still heating up...

TXTripper, your rpm and cooling problems are echoing mine exactly. If you are confident that there's no air getting into the system (doesn't take much) I would definitly get a new cap. My old cap's spring was weak enough I could compress it with my fingers. The new cap I couldn't. The one from Autozone wasn't good enough. I bought one like our van (1990 voyager) from the Dodge dealer. If you don't want to take the outdrive apart for redoing the intake system, seriously consider that clear hose technique. By the way, I'm at dsorrell@fedex.com
 

Peter J Fraser

Chief Petty Officer
Joined
Jun 22, 2003
Messages
598
Re: Still heating up...

You should also be aware that if topping up a cooling system that you should premix water and coolant conditioner to the correct proportions before adding to system. Also a point to note is that some types of coolant conditioners are not compatible when mixed together. Make sure that what you add is the same brand / type as already in use. If unknown then a complete flush and refill is in order.<br /><br />Regards.<br />Peter
 

dsorrell

Cadet
Joined
Dec 21, 2003
Messages
28
Re: Still heating up...

TXTripper, another thing I thought of - the book says that the thermostat will be wide open at 193. When I get to slightly more than one hash mark above 180, or about 198, my temp stays there while I'm running WOT. If I pull back to about 3000 rpm it will drop to between 180 and 196. This is all assuming the temp guage is accurate.
 

TXTripper

Seaman Apprentice
Joined
Jun 28, 2004
Messages
30
Re: Still heating up...

DSorrel-<br /> My temp gauge follows my up all the way to about 260, or so it reads. I don't quite understand how the clear tube method works, but I had a new cap put on the beginning of the summer. Did you get your temp. problems fixed? Was it the clear tube method? <br /><br />thanks-
 

Dunaruna

Admiral
Joined
May 2, 2003
Messages
6,027
Re: Still heating up...

Originally posted by TXTripper:<br /> Was it the clear tube method? <br /><br />thanks-
Replace a section of the raw water intake hose with a piece of clear tube. You can now see if air (look for bubbles) is entering the system.<br /><br />In my case, I have a clear bowl filter permanently in line.<br /><br />If you see air bubbles, refer to your previous thread with the diagram. Good luck.<br /><br />Aldo
 

dsorrell

Cadet
Joined
Dec 21, 2003
Messages
28
Re: Still heating up...

TXTripper,<br />Been away from the forum for a bit.<br />Yes, all my cooling problems are gone. I found out about the clear tube method AFTER I had done the other stuff. I may not have needed to redo all the water intake stuff in the outdrive had I known about that method. But I know it's good now though. My temp guage goes to 260 as well. At one point, not knowing how hot is hot, I let my engine get to one mark below max, 244 and wound up with no compression in cyl 1 due to a warped cyl head. <br />There's a lot of things that could be checked. Air in the intake system, clogged heat exchanger, clogged cooling path in the engine. You may just have to start eliminating them one by one.<br />Good luck, keep me posted. I'm pulling for you.
 
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