Heat Exchanger Problems High Temp NEW BOAT and still working out the bugs.

[NeedaBiggerBoat]

Running high temps and possibly hooked up wrong.

Where is the fresh water inlet hose?

I unhooked the T fitting and cranked the engine and water came out of the port side riser if I am understanding this correctly shouldn't the raw water be pumped to the heat exchanger first and out the risers last?




Well I drained the coolant and held a hose to every single line on the thing everything seems fine I am stumped as to why its overheating. When it was hooked up to the hose water was flowing really good through everywhere. I just need some direction here as it seems like it is the last thing that needs fixed before my vacation. The coolant was bubbling and boiling out through the overflow it seemed at idle after a run down the lake.

 

[NeedaBiggerBoat]

Re: Heat Exchanger Problems High Temp NEW BOAT and still working out the bugs.

Maybe I'm over reacting just a little and this wont be so hard to fix, planning to tear the front cover off the heat exchanger. Its weird because it seems to get plenty of sea water and the coolant side of things is what stays too hot the risers are way cooler the exchanger is cooler but the coolant boils and ends up emptying out into my bilge via the over flow the base\filler part of the exchanger is hot and the hoses upper and lower radiator are hot as well.

 

[HorizonblueDK]

Re: Heat Exchanger Problems High Temp NEW BOAT and still working out the bugs.

The raw water is pumped from the outdrive, through the oil cooler, and into the heat exchanger.

When you unhook the hoses that goes to the exhaust manifolds and fire up the engine, some water will come out there. This is because that some exhaust will escape that way, since is it easier than going througt the outdrive, which is under water. The water, that is in the cooling channels in the manifolds, are lituarally blown empty.

One common problem of overheating, are blocked exhaust risers. Over time, rust will restrict the waterflow through the risers.

 

[HCMQA]

Re: Heat Exchanger Problems High Temp NEW BOAT and still working out the bugs.

If your coolant is boiling AND you have good raw water flow. You have an internal engine problem not a raw water problem.

Your risers are cool because some of the raw water is bi-passed right to the risers the rest goes to the closed cooling which only cools the block.

Sounds like you may have a bad head gasket.

 

[NeedaBiggerBoat]

Re: Heat Exchanger Problems High Temp NEW BOAT and still working out the bugs.

If your coolant is boiling AND you have good raw water flow. You have an internal engine problem not a raw water problem.

Your risers are cool because some of the raw water is bi-passed right to the risers the rest goes to the closed cooling which only cools the block.

Sounds like you may have a bad head gasket.

Thanks I will do a compression check and see what happens. Headgaskets is no problem its the suggestions of other internal problems that worry me.

 

[Scott Danforth]

Re: Heat Exchanger Problems High Temp NEW BOAT and still working out the bugs.

what temperature are you running? with a heat exchanger, normally the engine thermostat is a 170 minimum, however many are 180.

what kind of raw water pump do you have? crank driven (via belt or coupler) or one in the outdrive?

when was the heat exchanger last cleaned out (the end caps)?

 

[NeedaBiggerBoat]

Re: Heat Exchanger Problems High Temp NEW BOAT and still working out the bugs.

Raw water runs off the outdrive impelled. Was running at 180 - 190 but got over 200 the coolant boils out at idle after a run.

I got a 160 thermostat to put in it and thinl the coolant might have been straight with no mix. No idea when the heat exchanger was cleaned everything looked decent but i am going to clean it with mutaric acid soon and take off the caps. It's a 1989 Four Winner Sundowner 205 350 5.7 there is no evidence of coolant in the oil or water.

 

[NeedaBiggerBoat]

Re: Heat Exchanger Problems High Temp NEW BOAT and still working out the bugs.

Heat Exchanger is out no clogs in any of the fresh water holes at all on either end there where some metal ships in the coolant side of the exchanger not very big at all. I flushed it out with tap water as best I could noting that on the coolant side of the exchanger looked fine.

I have been told that the water pump on the motor might not be circulating the water but I don't think that's the case. I still don't have a compression gauge at this time.

I did check the thermostat and boiled it at about 160 it started to open according to my thermometer.



I wish this was all fixed so I can at least get a few more times of enjoyment out of it and take it with me on vacation which I am very much looking forward to going on.

After finally getting it running and setting the timing to 8* I have RPM's all the way up to 4600 where thats supposed to be and I actually have a hole shot when before it took a while to get it on plane.

I was thinking about this also and it is dwell related but when I set the dwell with the engine running it is at 29* when accelerating the engine the dwell needle goes down, would these maybe have something to do with the timing and temp being high? I though that it just ment that the shaft in the distributor had some play in it.

 

[Scott Danforth]

Re: Heat Exchanger Problems High Temp NEW BOAT and still working out the bugs.

if your timing was way off, that will cause it to run hot.

while 200 is a bit warm for a boat, the same engine runs 230 degrees in camaros, firebirds and GM trucks without problems

who told you the raw water pump isnt pumping? you will need to verify that. it should pump about 19gpm at 3000 RPM

 

[NeedaBiggerBoat]

Re: Heat Exchanger Problems High Temp NEW BOAT and still working out the bugs.

if your timing was way off, that will cause it to run hot.

while 200 is a bit warm for a boat, the same engine runs 230 degrees in camaros, firebirds and GM trucks without problems

who told you the raw water pump isnt pumping? you will need to verify that. it should pump about 19gpm at 3000 RPM

Not the raw water pump that is definitely pumping I was referring to the water pump on the actual engine not circulating the coolant. the only thing that was hot was the engine and the upper and lower radiator hose the manifolds risers and sea water hoses were all still cool The timing is set to 8* and the dwell is at 29* exactly where it is supposed to be now it was set at 0 before and the dwell was 4* out of tolerence at 23* I have discovered 4 thing that I will try and do

1. make sure there is no air in the coolant part of the system when filling
2. mix the coolant 50-50
3. replace cap on heat exchanger the old one seems to be broken.
4. run without the thermostat and see if anything improves

I will then put the new thermostat in if I see some improvement.

It looks like the previous owner put a good bit of money into this as the cooling systems looks new along with the risers and manifolds. The engine was rebuilt as well. The only indication I have of that besides word of mouth was how clean it looked under the valve covers.

I will look to see if I can see the top of the pistons to see if they are clean to indicate to me that there is a head gasket leaking or not. I will do that in the mean time until I get a pressure tester.

Its just that this is all new and overwhelming to me I'm learning loads and enjoy working on it but at the same time I want to take it on vacation

 

[Scott Danforth]

Re: Heat Exchanger Problems High Temp NEW BOAT and still working out the bugs.

never run without a thermostat unless you use a restrictor plate. the coolant will be moving too fast otherwise and not pick up the heat from the engine and you will actually overheat.

if you suspect the circulating pump, buy a new on. with a closed cooled system, you can get away with a non-marine version (truck of same year as engine)

by the way, if your only getting to 200 degrees, the coolant is not boiling if you have a 50/50 mix. water boils at 212, and a 50/50% mix will boil about 228, and much higher when you have a pressure cap.

are you sure the heat exchanger wasnt just burping due to an over-fill?

 

[NeedaBiggerBoat]

Re: Heat Exchanger Problems High Temp NEW BOAT and still working out the bugs.

Put new coolant in and mixed about 50-50, replaced radiator cap with a new one because the old one was broken, and checked the engine temp with an infra red heat gun. All temps on the gun were 10* cooler than what the gauge read so I am assuming that the gauge is faulty. With the gun I got temps from 168* - 180* which is about normal from what I gathered with closed loop. This was on the hose at home and not in the water. Very good news and I am pretty sure that the radiator cap that was bad caused the coolant to burp out as my bildge was full of it.