Alarm driving me crazy...

[intrepidvoyager]

Re: Alarm driving me crazy...

re Knightgangs post about the thermo ...may really be on to something..... most of my experience is with closed systems as i am either on the west coast or in Hawaii ...don't know for sure, but seems to me in the merc raw water cooled system that full flow to the risers is not going to happen until the thermo opens completely ..and as your engine is apparently running below thermo opening temp that is not happening ......I don't have my merc manuals with me so maybe someone else can help on this point ....... I do have a bud here on Kauai that runs a raw water cooled 3.0 VP , but has run for the last 7 years without a thermo due to salt spray issues/ minimal engine compartment ventillation, etc. I'll see if I can get hold of my merc mech friend and let you know.

 

[intrepidvoyager]

Re: Alarm driving me crazy...

ok ..re the low engine temp and hot riser issue ...... all over here agree your engine is running way too low at 140 or so and wonder why you don't have a 160 thermo .....160 or so is the right operating temp for the engine.

know you changed the thermo but do you have the thermo head assembly with the springed check balls ? If so you may have the condition that they (the check ball/valves) won't open at higher RPM's/pressure .... which would account for the hot risers .....also if one is opening a bit and the other less or not that would account for one riser being hotter than the other. Dont mess with the spring tension as too weak tension will cause an overheat condition in engine water circulation.

Good luck and keep posting ...I am curious as to how this finally gets resolved.

 

[clinche]

Re: Alarm driving me crazy...

ok ..re the low engine temp and hot riser issue ...... all over here agree your engine is running way too low at 140 or so and wonder why you don't have a 160 thermo .....160 or so is the right operating temp for the engine.

know you changed the thermo but do you have the thermo head assembly with the springed check balls ? If so you may have the condition that they (the check ball/valves) won't open at higher RPM's/pressure .... which would account for the hot risers .....also if one is opening a bit and the other less or not that would account for one riser being hotter than the other. Dont mess with the spring tension as too weak tension will cause an overheat condition in engine water circulation.

Good luck and keep posting ...I am curious as to how this finally gets resolved.

WOW i really wish you can give the boat a look..not alot of mechs get in so much detail..i have been spending so much money with the problem still not solved thats why i decided to post..and im so appreciative of the fact you helping me out.

So it looks like i have a lot of work to do to diagnose this problem. I am sure i have a loss of voltage at the insturment panel. Battery voltmetre gives a reading of 13 at the instrument gauge however it gives 14.5 when connected directly to another voltmetre. I think this could be realted to the high oil pressure and probably erratic temp gauge however i think the latter is more of a grounding issue.

The thermostat is a 140 because the mechanic deciding to drop in a 140. really have no clue why. i bought a 160 kit with the whole gasket set and will replace. i will also replace the temp gauge send and temp alarm sender hoping that this will solve the alarm going off at abnormally low temperatures at the thermo. If not im sure this is a wiring issue, as you said.

Re: riser temp..i really cant understand why mechanics here insist that the readings i have are normal i have asked three independant mechs all saying the same..so im left with his question..how can i rely on one of these fixing me the problem when they believe nothing is wrong??

i am not technically inclined in marine engines..this is my first time owning an inboard engine so a lot of these things you suggested..the flappers in the Y going to the leg, the riser gaskets and many more things to check will have to be checked by a mechanic in 2 weeks time. i only buy the parts

So you are from Hawaii!! what a coincidence..me and my wife have just been there last May for our honeymoon and we looovvvveeed it.. I envy you what a beautiful island..stunning..we took a cruise and stopped on each island..we rented a car and visited so much places..If not for the distance i would come to Hawaii every year but me living in Malta (very small island near Italy) makes this next to impossible to do.

I think i said to much now however i really appreciate your input and you talking my problem out with your folks. I will keep you posted with any news.

Thanks a lot

Aloha

 

[Knightgang]

Re: Alarm driving me crazy...

I am not trying to knock you, but you will spend alot of $$ with marine mechanics, especially with troubleshooting... Shop time is still shop time and gets expensive...

If there is anyway possible that you can get a mechanically inclined buddy to help you look it over and turn a few bolts to diagnose, then that will but you a few steps ahead...

I know this is not always possible, but you seem to have a little more mechianical sense than you are giving yourself credit for...

Just a suggestion. If you really trust you mechianic, then that is something else to consider...

 

[fossill]

Re: Alarm driving me crazy...

Did you check the "check valves" in the upper tee of the the thermostat housing. The hoses from there go to the risers. I'm not sure if your engine has them, but my 4.3 does. If they were to stick or jam partially closed, that would cause a major flow restriction to the risers. One riser will run hotter than the other according to the maintenance manual due to the coolant flow pattern in the engine which is normal.

 

[intrepidvoyager]

Re: Alarm driving me crazy...

Aloha .....fossil and i are on the same page re the check balls in the thermohousing .... you don't need a mechanic to check these and as we both surmise this could be the problem ...to be absolutly sure they are operating properly I would get a new set and compare the spring action on yours against the new .....if the spring action is too weak your engine cooling will be adversly affected .....if too strong or hung up, you will reduce flow to the risers....if all is well you can return the new ones ...on another issue i will check and see if its possible to put the riser gaskets on wrong on your set up and get the temps you are getting ...... is this the manifold riser set up you have ?

http://www.oceaneastmarine.com/GLM58232.jpg

you know a lot already ( also previous post ) about how to find problems so if you don't have, you should get a seloc manual on your engine ...about $40

the more you can figure out yourself the better ...like when you are out in the middle of nowhere kind of thing.

and finally I don't know why the mechanics there say your high riser temps are ok ..... there are plenty of articles on the web like the one i previously sent (about the alpha set up ) that outline how the system works and what proper engine and riser temps should be !!!! as I said re the risers on our big block Rinker ..at 3800 RPM ..you can hold your hand on them. .... engine coolant temp on the guage is 160.

Oh ....... and as an aside i am not a pro boat mechanic ... just an old mechanical engineer who has been messing around with boats for 40 plus years . right now I am stuck on Kauai helping the locals fix thier boat problems
....trust me, its good to ingratiate yourself with the locals.....there was a guy called Cook here many years ago that didn't ...so they had him for dinner

 

[intrepidvoyager]

Re: Alarm driving me crazy...

OK ...hold the phone re buying a new guage and sender ..... here is what to do ......pull the temp guage and the sender ......run a new wire ..same diam as the existing sender wire ...probably 16 guage from the sender to the s terminal on your temp guage ..... run a new wire from the battery to the pos on the guage and a new wire from the neg on your battery to the ground on the guage and a wire from battery negative to sender housing to ground the sender like its screwed into the block......ok now borrow your best girls hair dryer or use a heat gun and heat up the sender sensor ...great you got an ir thermo as now you can check the reading on the guage against the ir at the sender ...if its reading right you got a wiring harness/ground/pos to ip problem ...if its off .... buy a new sender ..BUT ...you got to make sure that the resistance range on the new sender matches the guage ...... so for example if its Fraria call there tech line ..get the range and buy an appropriate sender .... the one in your boat may not be the right one for the guage ....ps ...you can do this at home on a car battery like maybe she won't let you take her hair dryer down to the boat ... .....now if the new sender does not solve the problem ...its the guage .....you can alter the resistance range of the circuit but you are getting into funny stuff using a variable resistor from an electronics shop so best to go with a new guage.

 

[fossill]

Re: Alarm driving me crazy...

You ARE overheating your engine. 200 degrees at the risers not good. You should be able to touch those things running wide open.
The reason the alarm is turning off at the lower RPMs is that you are getting more water volume at the lower RPMs.
Instead of replacing the equipment that is screaming at you, try replacing the fresh water pump AND housing. You have wear in there and the impeller is losing its seal against the housing or wear plate. This causes lowered water pressure, which means loss to your heat transfer efficiency.

Well, I don't know about being able to touch the risers. Once that engine is warmed up fully, the riser will at least be the temp of the coolant..160 degrees, which will be the temperature of the water cooling it.

 

[fossill]

Re: Alarm driving me crazy...

I'd say you got an indication problem. To verify, go out and buy a cheap mechanical type temp gage and hook it up temporarily to the engine (in place of the original temp sender) and run the boat. If it runs in spec, everything is ok mechanically and you got a problem with your alarm/electric temp gage setup. There is a service bulletin out from Merc advising the use of a 140 thermostat for engines that have a "run on" problem, so its not out of the ordinary to have that thermostat in there.
I mentioned the check valve thing earlier because it is possible for those to stick if someone replaces the hoses with the wrong type. I doubt you have a problem with the risers runnning that warm. Remember its being cooled by basically hot water, the temp of the engine, and then more heat being added to it from the exhaust gasses.
The risesr on my boat also get very hot and its a brand new boat.

 

[Knightgang]

Re: Alarm driving me crazy...

Well, I don't know about being able to touch the risers. Once that engine is warmed up fully, the riser will at least be the temp of the coolant..160 degrees, which will be the temperature of the water cooling it.

There is a higher percentage of cooling water that is bypassed at the thermostat housing that is dumped into the risers than the water that actually flows through the engine to cool it.. Therefore, yes, the risers should run cooler than the engine coolant temp. and cool enough to rest your hand on...

 

[fossill]

Re: Alarm driving me crazy...

Well I could be wrong, but according to page 6A-30 of Mercruiser manual #25 ( I assume other Merc small block V engines are similar) the coolant flow to the risers flows directly out of the thermostat with nothing being bypassed.

 

[Knightgang]

Re: Alarm driving me crazy...

For example the circulating pump on a standard small V8 GM based engine will flow approximately 50 gpm through the engine. The typical raw water supply pump inside the Alpha sterndrive is capable of flowing about 18 - 20 gpm depending on the gear ratio and restriction the system experiences. A standard 300 Hp small V8 engine dissipates approximately 300,000 Btu/Hr of heat into the coolant. To maintain a thermostat temperature of 160 degree F at wide open throttle this engine would need a pump to flow about 8 gallons per minute (GPM) of 70 degree F water into the system to maintain this engine temperature. Since the Alpha raw water pump can flow 18-20 GPM there is significant bypass (excess) water supplied, which therefore has to be dis-charged somewhere.

In a cold manifold system the warm water that flows through the thermostat, as well as this excess bypass water are joined together in the thermostat before exiting and being introduced into the bottom of the exhaust manifold. The fact that your are mixing together a lesser amount of 160 degree F engine water (8 GPM) with 10+ GPM of cold lake water allows the aggregate coolant temperature in the manifold to fall below the 110 degree F threshold needed to prevent the accumulation of condensation in the exhaust system.

Well I could be wrong, but according to page 6A-30 of Mercruiser manual #25 ( I assume other Merc small block V engines are similar) the coolant flow to the risers flows directly out of the thermostat with nothing being bypassed.

The Bypass mixes at the thermostat housing... Read the section above from intrepid and you will see that there is excess cooling water that has to go somewhere...therefore the bypass passages at the thermostat housing and that is how th riser temps are kept lower...

 

[intrepidvoyager]

Re: Alarm driving me crazy...

ya knightgang ...that's the ticket ...

Anyway Cliche ...let us know what the verdict is on the check balls .... then we can tell you how to test the whole system up to the risers on the hard....if that works ...then got to be the risers ......talk to any boat mech thats been around for a while and he'll tell you that risers can get plugged up in 4 months..or maybe a gasket issue .

You did the impellor ... right ???

 

[fossill]

Re: Alarm driving me crazy...

Oh ok. I thought the two ports on the thermostat housing were not interconnected and separate by looking at that coolant flow diagram. Learned something new.

 

[intrepidvoyager]

Re: Alarm driving me crazy...

hey fossil ....too bad you got that handle ...I'm so old that that's what all the youngsters around here call ME !! ....anyway I still learn new stuff ... here's a cute one recently from an old timer on how to test an oil pressure guage/sender ....wire up the guage/sender to a battery.....get hold of a bicycle pump with a built in guage .....hose it up to the sender and pump away ....... if the dash guage reads as the pump guage you got an on board wiring issue ....if there is a diff ...you probably got a bad sender or one with the wrong resistance range ....now here is the fun part ...you can fool the guage into reading higher or lower by adding or subtracting resistance using a variable resistor .....too cool for school !!!!!

Cheers

 

[clinche]

Re: Alarm driving me crazy...

really good point Knightgang re the thermostat.....also maybe should check that your hoses to the manifold and risers are not inverted ....

http://ocranch.us/tmp/v8cooling.jpg shows the correct layout .

I'd pop over to have a look, but sorry I'm stuck on an island in the middle of the pacific with a bunch of hula girls ...75 degrees today ...hope you guys arnt freezing to death

Hi Interpidvoyager,

Mechanic(a friend) is coming next saturday for a full service. With that said i am going through the thread and am jotting down some tests that you and other folks suggested which i can test out with the mechanic(a friend) .

I noted something strange with my system and the one in the diagram you sent me. I have no water hose between thermostat and riser. The hose coming out of the thermostat goes directly into the manifold and thats all there is to it. Is that a problem? Is it normal?

This is my colloing system:

Water Hoses:
http://www.perfprotech.com/store/assembly/Standard-Cooling-System,2697-110.aspx#assembly

Manifolds & Risers:
http://www.perfprotech.com/store/assembly/Exhaust-Manifold-And-Exhaust-Elbow,2697-100.aspx#assembly


Thanks once again...

 

[Knightgang]

Re: Alarm driving me crazy...

Looking over the diagrams of the cooling hoses, it appears that your cooling hoses can either 1. go from thermo housing into riser (exhaust elbow) or 2. Go from thermo housing into manifold.

I would think that into the manifold (like you said it is) is the most effecent for cooling purposes...

I would besure that the passages in the thermo housing are open and that there is no debris in the hoses to the mainfolds and that you have good water pressure and flow through there...

 

[intrepidvoyager]

Re: Alarm driving me crazy...

your set up is fine ....... only problem is this is a bit hard to test without the leg actually in water ....... you cannot take the chance of getting water in the engine by running hose water, engine off, thru the manifolds to see if there is a blockage in the manifold/riser ...... if you can get the leg in a big bin fed by a hose that would be great ........ watch that the water level in the bin does not get too low as your raw water pump can pull up to 18 gallons a minute . ..

STEP ONE ..... start the engine and let it run up to thermo temp ...now check both hoses running from the thermo to the manifolds ..... if they are hard and cannot be squeezed at all you have a blockage in your manifold/risers or the manifold/riser gaskets are wrong or improperly installed.

Also check that there are no bits of old impellor blocking the hose at the manifold cooling water inlet on the bottom of the manifold.

If the hoses can be squeezed ..... there is water flowing thru them but should not be under a lot of pressure .... OK turn the engine off .. if this test is ok .....then go to step 2

STEP TWO

...... now you know what 18 gallons looks like ....if not measure it out .... ok put a piece(s) of ply over most of the bin so exhaust water does not go back in the bin ........ take the hose feeding water out of the bin .... now start the engine at zero seconds on your watch and keep an eye on the water level in the bin ......... so the idea is to see how much water your pump is pulling ....in 30 seconds should be around 9-10 gallons ......if its less than that you got a raw water pump issue or some blockage in the raw water line/ps cooler/thermo housing

good luck ....let us know

 

[intrepidvoyager]

Re: Alarm driving me crazy...

oops ...forgot .....symptoms of riser blockage can also be flappers in the Y exahust tube.

 

[clinche]

Re: Alarm driving me crazy...

oops ...forgot .....symptoms of riser blockage can also be flappers in the Y exahust tube.

Thanks. I'll perform these tests next saturday and will keep you posted.

Is it difficult to check the power steering cooler for any debris given it's location?