Inboard engine overheating!

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Aquabell27

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I have a 180 ford mermaid shaft drive engine and it is overheating when I open it up, I have just fitted, a new heat exchanger (2nd hand) due to the original tube stack leaking, I am not losing any coolant now, Inter cooler and oil cooler are all free from debris, new impeller and plenty of water coming out of the exhaust. Iam wondering if there could be a build up of sludge in the fresh water cooling system, is there any recommended products that would flush this through? Any help or advice would be greatly appreciated
 
Not familiar with the Mermaid, but could the FW system be air locked somewhere. On my VP TAMD60c s I have to vent at the turbo with the engine running, and the vent plug is tucked away where you can't see it, and the turbo rapidly gets very hot.

What temp is the exhaust say 1-2' downstream of the water injection point. If not more than 40 -50c then I would look at it being the FW system. If your seawater is getting hot then insufficient seawater flow.
 
On my Volvo Penta AD31 engines I had to rev the engines hard for at least 30 seconds to force the air through the raw water system after I cleaned my heat exchanger. Given your symptoms have you been out on the water since you carried out the repair work, or was it overheating prior to doing the job?
 
Seawater is cold, there is definitely sufficient seawater flowing through, there are no leaks on the fresh water side, I do have a valve near the turbo which is used to drain the fresh water system, gave it another run today and it warmed up once I opened it up again unfortunately
 
Did you take a look at the thermostat when you had the header tank off?? sounds like the raw water is going through at a good rate, also check the "fan" belt tension. Remove the filler cap the level needs to be 1" below the neck, start her up, did she gush water out? no, then that seems to be ok, with the cap off allow engine to warm up, are there any needle bubbles going around? no, then the head gasket would appear to be ok. What is telling you that you are getting hot? the gauge? not to be relied upon, try a thermometer one of those laser beam types, point it at the head were the sender is, and check the gauge and it read the same. Feel the jabsco pump it should be stone cold, check the sea water inlet valve while your at it.
 
Yes I did have a look and it seems to be ok, the boat was fully rewired in the last 2 months with all new gauges so I would be reluctant to think that it could be a faulty gauge but I may try the old 1 to see how that fairs, I will also warm the engine up with the cap off, iam wondering if iam losing pressure somewhere but the filler cap seems ok, however when I took it off with the engine hot today there wasn't a noise of pressure being released.
 
Aquabell27 said:
Yes I did have a look and it seems to be ok, the boat was fully rewired in the last 2 months with all new gauges so I would be reluctant to think that it could be a faulty gauge but I may try the old 1 to see how that fairs, I will also warm the engine up with the cap off, iam wondering if iam losing pressure somewhere but the filler cap seems ok, however when I took it off with the engine hot today there wasn't a noise of pressure being released.
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Strange, you were lucky not to have got scalded! when you fitted the new gauges did you fit new senders?

Get one of these!
http://www.amazon.co.uk/thermometer...ter laser&page=1&rh=i:aps,k:thermometer laser

they may save a visit to the hospital,one last question are you 12 or 24 volt?
 
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I have waterproof/ heat resistant full sleeve gloves and a towl! Iam 24 volt but have a converter on the gauges as they run on 12v. yes all new senders were fitted aswell
 
Aquabell27 said:
I have waterproof/ heat resistant full sleeve gloves and a towl! Iam 24 volt but have a converter on the gauges as they run on 12v. yes all new senders were fitted aswell
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If that engine had been up to temperature and you removed the filler cap you would need more than gloves I can assure you. I still suspect the "electrics" are they VDO? or some Chinese ones. Get a thermometer onto the job.
 
The gauges are faria gauges from asap supplies so I believe they are good quality ! I will let you know my progress over the weekend....... Thankyou for your help
 
This might be a daft question as I'm not familiar with your setup...

When you say you've changed the impeller - I'm assuming raw water? Is there a water pump to circulate the fresh water too and is it working? (blade missing, seized, sheared internally etc) Otherwise I presume the heat would build up in the engine and no amount of cold water through the heat exchanger would help? What temperature are the fresh water hoses in/out and are they hard/pressurised or soft?
 
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