SP 230 overheating? 195 -200 degrees

Author Message   Peter C. E. Rubens New member Username: migmatic Post Number: 1 Registered: 10-2009 Posted on Wednesday, October 21, 2009 - 03:55 am:    Helping a friend with overheating problem. He got it up to 250 degrees running it flat out there was some "smoking"(steaming)from the engine. The steaming problem was seal on back of impeller drive leaking water and from "o" rings leaking around back of heat exchanger dropping onto drive belts and flinging it off in all directions and the block evaporating the water,...hence the "smoking",... problem solved. I found the outdrive hose not fully on the connector, new hose and clamp installed. Those were the ONLY noticeable problems. I read lots of the posts here about overheating problems and have heeded all of them! Cleaned outdrive Poked wire up drain hole to where water flows through to connector, clear New hoses/seals/"o" rings from outdrive to freshwater pump, all Volvo Rebuilt freshwater pump using the Volvo kit New impellor New freshwater filter and "o" ring for black filter cap New "o" rings/seals in heat exchanger, again Volvo Cleaned heat exchanger, muriatic acid, no blockage a few small bits of impeller,...that's all! It is a heavy unit,(heat transfer?) New water pump New seals from exchanger to exhaust manifold New sensor in block New thermostat,... 86 degree?,...whatever,... it is the correct one from Penta All brass pipes unobstructed, no holes. Absolutely NO leaks from either engine freshwater input or engine coolant, no suction issues on freshwater side. That's the nice thing about new seals! It is run in freshwater only so corrosion is not an issue, (VERY minor pitting). Water exits lower unit and I lose no engine coolant. I have NOT removed the Exhaust manifold. Why?? Because there was nothing in the heat exchanger so its' logical to assume the exhaust cooling system is(must be!)just as clean,...but it is on my list if I don't figure this out!! Engine head gasket was changed, and carb rebuilt several years ago by a reputable boatyard. So here we go! Engine a little cranky to start, timing is fine, fires on all four, (idles a little high at times 1100-1200,..searching). I've run at idle and on the lake up to 3200 RPMs (flat out at that trim). The temperature at idle is about 196 At full bore,...200 to 205. I NEVER exceed that and so no where near 250 that my friend saw! My questions, 1. Is this a reasonable temperature range to run this thing? (Well,it isn't "smoking" anymore!!). 2. Can and should I try to run a cooler thermostat in place of the one recommended by Volvo. (But then again why,...I know it opens and circulates water to the heat exchanger,...I am just running too hot. So if it opens at a lower temperature I'am still running it up until it would get too hot). 2. How much water should run out the freshwater filter if I take the black cap off. I have a continuous flow more than overflowing but not "gushing". And on this point should the water exiting the heat exchanger on it's way to the exhaust manifold (in the copper pipe)be cold or very near that? The red exterior of the heat exchanger is HOT but I wonder why this doesn't seem to transfer to the freshwater flowing through the copper heat exchanger very well? The exhaust manifold itself is also cool to the touch. Problem??? The only other thing that could even be remotely possible, (the way I see it) is a head gasket problem, (the wrong gasket blocking off cooling passages??)But hey it was a reputable engine place who fixed it!! I've owned several of these engines,...in the car, so I do know my way around them,...but this is a boat with a marginally designed cooling system! Sorry about how long this post is but I don't want to hide anything! El Pescador, et al any suggestions? if I spend any more money it will be a new engine Thanks All, Peter   Ricardo E. Advanced Member Username: ricardomarine_vp Post Number: 698 Registered: 03-2009 Posted on Wednesday, October 21, 2009 - 10:39 am:    My questions, 1. Is this a reasonable temperature range to run this thing? (Well,it isn't "smoking" anymore!!). Yes! See your OEM manual for the correct temp range! 2. Can and should I try to run a cooler thermostat in place of the one recommended by Volvo. (But then again why,...I know it opens and circulates water to the heat exchanger,...I am just running too hot. So if it opens at a lower temperature I'am still running it up until it would get too hot). The thermostat holds back coolant until the "On Demand" principle goes into effect! 3. How much water should run out the freshwater filter if I take the black cap off. I have a continuous flow more than overflowing but not "gushing". And on this point should the water exiting the heat exchanger on it's way to the exhaust manifold (in the copper pipe)be cold or very near that? The red exterior of the heat exchanger is HOT but I wonder why this doesn't seem to transfer to the freshwater flowing through the copper heat exchanger very well? The exhaust manifold itself is also cool to the touch. Problem??? This may indicate that your sea water system is doing as it should. Have you removed and inspected the engine "Circulation" pump? El P will likely have some good info to add to this! .   Peter C. E. Rubens New member Username: migmatic Post Number: 2 Registered: 10-2009 Posted on Wednesday, October 21, 2009 - 05:24 pm:    Hi Ricardo 1. OK I don't have the manual, (I know I should at least have that!) But I'll get it and check! 2. Yes I see your point on the thermostat. In fact I can see a slight spike in the temperature just seconds before it opens and then the temp. drops a bit then rises only slightly, (and never above 200 degrees after that). 3. I have a brand new circulating pump, gasket and rubber seal to head. It is perfect. Thanks for your reply! Peter   El Pescador Senior Member Username: el_pescador Post Number: 4994 Registered: 02-2006 Posted on Thursday, October 22, 2009 - 12:04 am:    Peter, the coolant temperature range for the 230 is 180º-198ºF, so I think there is no cooling problem. Maybe the boat is overpropped and that's why it runs at the limit at WOT? BTW, what are the WOT RPM? The engine is nothing but an AQ131 coupled to an SP drive. Here is a link to the operator's manual. http://vppneuapps.volvo.com/ww/PIE/ViewFileFrame.aspx?n=172178&r=2008-10-29-17-5 3-18&t=PDF&a=7746277&p=T403&d=OwnersPublication&s=15176602&lang=en-GB A clean heat exchanger does not mean a clean exhaust manifold. Exhaust manifolds (unless custom made in stainless steel or other metal) are made of cast iron, and they corrode even in fresh water.

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