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BF200 overheating

K

Kstafford

Contributing Member
So my maiden voyage resulted in my starboard engine overheating as soon as i went to plane. I replaced the thermostats and impeller unit a few weeks back and both engines ran beautifully for 15-20 min at idle and revving up on several occasions right off the old muffs no issues at all. As soon as i put in i noticed the starboard had week flow and was hopping it was a little air bound not the case. I dropped off the leg when i got home and found lots of crap in the impeller housing like large sand flakes of mineral deposits. took out t-stats flushed down with hose more garbage came out. Put pack together and it still overheats in 5 min or less temp readings are 190 ish at top of manifolds just before it screams with good flow from the tinkler. 2008 motor with 330 hrs and i know they were never run hard witch is the issue. So t-stats out i will Flush with Vinegar and am considering barnacle buster. However Barnacle buster and aluminium seems to be a great debate what else may i be overlooking here......
 
I’ve done straight vinegar with an aquarium pump from the T stat down (leg removed) to a bucket. Circulated for a while, then switched areas in the t stat housing (I have a 150). I was not overheating but was able to get some stuff out. If you had that much stuff out, tour tell tale will eventually fill up as well. I had to clean out the cooling on the vst because of this.
 
I did a vinegar flush for three hours and it seems to have cleared itself I was running it pretty hard with hose connected to the intake tube with the lower off and I couldn’t get the head temp over 158F until I compare it to my port engine anyone know if that’s a good number ??? Thanks all
 
158 F is excellent! Spec is 160 F. Having said that, you need to do a hard run and check it again.

Many years ago I installed surface temp senders on each cylinder head of my BF 225 so I can monitor temperature in all kinds of conditions. If you are interested in doing that, send an e-mail to me at [email protected] and I will send back a write-up of how to do it.
 
Bad news leg on in barrel still overheats at 190 on starboard side only port is at 150 when it happens. The tell tale comes out steady for a bit the it blurbs every now and again my port engine is a steady stream is it pulling air somewhere HELP!
 
Took out the starboard PRV found it was not stuck at all some crud also small hose barb going to VST completely plugged up freed up reinstalled and it overheated even quicker WTF soooooo pretty sure it’s getting the acid douch Barnicle Buster next step change my mind.....
 
It sounds like this sat for a while and had quite a bit of stuff plugged up. I’ve heard of people pulling the Tstats off, pulling lines downstream then running a hose on high pressure through the tstat with a towel around it to force stuff through. I’ve never done it as I was afraid to soak the engine with the hose.
 
What TritonFisher described works fine. I've done it several times to get sand and mud out that got ingested while trying to get on my lift at low tide. Suggest you try it - with leg removed. Put a big bucket underneath to see what comes out.
 
I started there all open full city water pressure through every available hose opening large enough I feel as though I’m just moving the problem around and it’s time to eat that crap alive with some acid I know everyone is afraid to use stuff like Barnicle buster but I feel it is a good solution to this issue with very minimal risk I have tested it on zinc and aluminum and the effect is minimal at best the mineral plug that I removed melted like butter.
 
I have no experience with Barnacle Buster, so cannot advise.

If you try it, let us know the results.

However, I would first drop the leg again and do a close inspection of the water pump and impeller. Recognize that if mud and sand get ingested into that pump, it can quickly wear the liner that the impeller vanes seal to.
 
i will update just a nice recap here

1 bought boat sea trialed for 45 min all rpm conditions i have twin 2008 bf 200's 330hrs NO ISSUES
2 proactively replaced all tstats impellers plugs HP LP fuel filters Mid shaft bushings.....
3 Ran both engines on ear muffs several times varying RPMS for 15 -20 mins at a time NO ISSUES
4 Launch boat in salt water where it has always lived starboard Eng instantly shows weak telltale flow.
5 survived 15min no wake zone but immediately overheated once on plane.
6 droped leg at home found lots of desbree in impeller housing removed tstats flushed good with city water pressure up down and in between
7 bolt up leg and run telltale worked and plugged instantly
8 remove t stats drop leg flush out good both ends more crud in impeller housing and out of tell tale pipe.
9 ran vinegar bath for 3 hrs tstats out leg off bilge pump circulating directly up intake tube more crud came out maybe 1/8 cup total organic crap mostly.
10 ran motor with city water pressure directly in pick up tube temp numbers were beautiful even at 3500 rpm for 5 min straight key City water PSI.
11 leg on in barrel overheats in 10 min starboard 30 degrees hotter than port.
12 removed starboard PRV return line fitting from VST blocked solid with a good amount of crud under popit valve as well clean flush lines resemble.
13 fully cooled off run in barrel overheats in 5 MINS NOW ??? get pissed off.
14 when i get home today i will check the port PRV and if it is clean it is going to get the acid hose jammed up its *****......
 
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My guess as a long shot is that i know the previous owner putted around mostly and used infrequently 330 hr on 12 year old motors. I have inspected a lot of the raw water passages and parts and surprisingly there is very little amounts of corrosion/build up where i can see. I am sure the motors were rarely flushed if at all. Perhaps the new impellers and all the muff running i did was enough to stir all this crap up.
 
No go bucket of acid was pretty nasty brown after one hour seemingly no improvement. Ran in a barrel weak stream at idle will overheat if I rev it up or run at higher rpm it is fine and dandy fully pissed at this time. I also swapped out lowers with my port unit that works fine just to rule out the impeller setup same results overheated at idle
 
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Explain the picture. Don't know what I'm looking at.

From your post #13, do I understand correctly that you only get the overheat at idle or low RPM's?

Have you pulled fault codes? That may pinpoint which sensor is triggering the overheat alarm. A code 24 is sensor #1 which sits on the top of the starboard side manifold. A code 25 is sensor #2 on top of the port side manifold. A code #6 is the ECT (block heat sensor.) See below.

If you don't have one, buy an IR heat gun (they're pretty cheap at any auto parts store or Harbor Freight) and confirm that you are truly overheating. As the engine is warming up, quickly aim it at each cylinder head and each manifold and see if one section is heating up faster than the rest. That could help pinpoint a blockage, if there is one, and would confirm the overheating.

Have you pulled and inspected the heat sensors themselves? There is one on the top of each of the manifolds. There is a 3rd heat sensor for the block, and that is down in the V of the engine and is a real PITA to get to - requires removal of at least one head.

Confirm that those new thermostats are working properly - it's possible one could be faulty. Put them in a pan of water and heat it up. They should begin to open at 140 F and be fully open at 160 F. Full open is only 3 mm.
 
The picture is the filterd out garbage from the acid bath... i used vinegar first round and got about the same amount of garbage out of the motor. You are looking at the results of the second round which was barnicle buster mixed per instruction and circulated leg off stats out for a hour and 10 mins.
it only overheats at idle and i have confirmed the temps all along with a IR thermo it reads 190F on the starboard ECT just before it goes into alarm with very week flow from the tell tale. Port side temps are fine I boiled and checked the brand new stats and they are good. I swapped lower units as i have twins to eliminate possible impeller issues which gave the same results over heats on starboard side at Idle. At 1000-3000 rpm for any length of time and it runs at 145 on the ECT and a head temp of 165. I have Removed every hose inspected and blown out every orifice i can reach outside the motor inducing both small and large rubber tubes at the bottom of the exhaust manifolds, VST lines and both PRV units. When i get home i am going to attempt to somehow isolate circuits in the system and water flush and used compressed air in hopes of a golden nugget falling out somewhere. If that does not work than i will try the acid bath from the top down. The tell tale is not consistent in flow it burps and seems aerated also gets pretty dam hot. My fear is a rot through that is mixing exhaust gasses into the water jacket. or maybe it is normal when running in a barrel IDK.......... Also i have not checked error codes mostly because i can whatch it over heat real time with the IR scanner.
 
Also thank you for taking interest in my trial and tribulations CHawk I appreciate all the help as I am reach the end of my rope here!
 
OK. Understand. I wasn't going to say anything about the possibility of a corroded head/block or blown head gasket until we tried to eliminate all else. However, if you are getting exhaust in the cooling water, I would think that it would show up in the barrel. Aerated water coming out of the pisser is troubling - that shouldn't be happening.

Have you checked the seals on both ends of the water tube coming out of the water pump?
 
I haven't checked the motor side seal yet on the tube i will and would also think with the stats out city water pressure in the pickup tube for as long and as hard as i have been running it by now it would have hydro locked or be getting some milky oil in the crank case by now fingers crossed.... I am borrowing a FLIR IR cam from work so I am about to get real scientific on its *** Also the pisser hose has a tinny pinhole in the back of it but even when i covered it with my finger it still looked to be bubbly stream.. The quest continues.
 
Back flushed again today and got a bunch more stuff out of the motor. With the leg off and the garden hose attached directly to the pick up tube I get no air bubbles at all a steady stream coming from the pisser. I left the volume low enough to replicate the other motors stream at idle. It does not overheat and runs at normal temperatures highest 170 on the head the Manifolds highest 145 at the top cylinder the middle cylinder on the manifold runs at 1:15 the bottom cylinder on the manifold runs at 1:05. When I run in a barrel with the leg back on there are lots of bubbles in the piss stream and the motor will overheat quickly. The only encouraging thing I saw was that both sides of the motor seem to be running at the same temps now. A 30 degree temp increase from the middle cylinder to the top cylinder on both manifolds seems a bit suspicious ED8EB91A-E357-413E-B68D-835F4775FF9C.jpeg
 
I think flushing through the thermostat down is your next best option, even with the barnacle buster. If possible, rig your pump to go into the tstat housing and have the bucket under the pickup tube. Let it cycle for a while. I’ve also read that the water temp you mix barnacle buster with has an effect.

Im not as familiar with the 200, but what about the poppet/pressure relief valve?

Btw I was in a similar situation—-boat had ~84 hours and was 12 years old. After our freshwater vacations the telltale always plugged up because something got worked through the system.
 
My closing statement unless my next sea trial is bad is that it is fixed and the issue was human error. My barrel was not deep enough to cover the primer hole in the pump housing an thus I’m a dumb ass. My original problem was crud forming a blockage in my cooling system. I solved that problem with Barnicle Buster which works very well. The sheer amount of crap that came out of these motors was amazing and appalling. They both run 10-15 degrees cooler now and I know they love me for this. Stay calm cool and collected out their fellow boaters and don’t over look the simple things!!!7963159A-86A2-4A01-B3BE-E18BAC86BFB4.jpeg
 
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