Water on #7

[Sparkey scott]

Hi folks I have a 1979 formula Thunderbird 1 owner and garage kept. I have water dripping down on to the piston #7 . I have replaced the head intake and exhaust manifold with no change . With the plug out and up to temp with water on the foot I can see water dripping down please help this is a great looking all original boat and I'm ready to have some fun with her

 

[Bt Doctur]

unless you have X-Ray vision or are using a bore scope you can`t see inside a cylinder when the drive is pumping water, meaning the engine is running.

 

[Scott06]

Just to clarify what engine is in there ? You have replaced the cylinder head, intake and exhaust manifold? If that's correct only thing left is cracked cylinder wall. Would have to replace block or sleeve that cylinder. What's The history on this engine was it subject to overheating !

 

[HT32BSX115]

Hi folks I have a 1979 formula Thunderbird 1 owner and garage kept. I have water dripping down on to the piston #7 . I have replaced the head intake and exhaust manifold with no change . With the plug out and up to temp with water on the foot I can see water dripping down please help this is a great looking all original boat and I'm ready to have some fun with her

Howdy,

Welcome aboard!

Well, to start with, it will help if you tell us what engine and drive you have to include serial number.

Year & model of the boat tells us nothing.

Mercruiser uses serial numbers to identify and many boat manufacturers will use last years model engine and drive combinations.

Pictures also help,

Regards,

Rick

 

[Scott Danforth]

If the block is cracked, replace the motor

 

[Sparkey scott]

The boat history is good I know the owner and he has given me all receipts from new to present day I talked with him and he said never ran hot and always winterized even have original owners manual he said back in the early 80s he had the same problem and was a cracked exhaust manifold I am doing the work myself as I have a good mechanical background while I had the head off I inspected the cylinder and all looked great the boat only has 250 hours and always fresh water I will post engine and out drive serial #s later would a bad riser elbow cause water on top of cylinder thanks folks

 

[Bondo]

would a bad riser elbow cause water on top of cylinder

Ayuh,..... Welcome Aboard,..... Yes, it most certainly will,.....

Leadin' cause is the failure at the riser / manifold gasket interface,....

 

[Sparkey scott]

Ok thanks Bondo here are some serial numbers first is engine (5)270638 next is stearn drive 5095136150R my riser has two gaskets with a stainless plate sandwiched between I'm ordering a elbow riser today and a new set of gaskets trying to post a picture but says file too big I'll figure it out

 

[Lou C]

Also it is very important to inspect the sealing surfaces of the manifolds and elbows (risers) to make sure there is no erosion of the sealing surface. Minor defects can be cleaned up by a machine shop but if its extensive it may be time for a new exhaust system if you want to keep water out of the cyls.

PS a cyl head can "look" good but still be cracked and let water in. Any history of overheats?

 

[Sparkey scott]

No history of over heating but she has been sitting in a garage for 5-6 years

 

[Bt Doctur]

If this is fresh water cooled on a full system (engine and manifolds) then you will have a SS block off plate there.So if it`s AF leaking in its a manifold or gasket, if its water its an elbow or elbow gasket.

 

[Sparkey scott]

Thanks Bt Doctur I'm very new to boat from what I know or think I know she is raw water cooled has no place for antifreeze and has no expansion tank there is a water pump in the foot and a water pump on the front of the motor I replaced the exhaust manifold because there was water inside the manifold when I removed the bolts holding it to the engine water ran out . I was short 1 gasket as you said I have a gasket then the stainless plate then another gasket I made a gasket but not confident so I ordered a new riser elbow as this is original so 40 years old and a pair of gaskets fingers crossed that this fixes it and I can enjoy this great looking boat on the water

 

[Sparkey scott]

Ok I tried new riser elbow gaskets today with the old riser . Ran fine untill the thermostat opened and water started exhausting from close to the transom at the out drive . My question is would it hurt to close off the water hose going from the thermostat to the exhaust riser elbow just to prove a point any help is appreciated

 

[Baylinerchuck]

water should be flowing into the exhaust elbows as soon as the motor is pumping water. So I don’t think that would really prove anything.

 

[Scott06]

As above water should be moving to elbow entire time it's runnig to cool exhaust and coming out the exhaust relief ports on transom housing separate from thermostat opening to cool the block and heads. What difference did you notice when thermostat opened?

 

[Sparkey scott]

Well water only comes from transom once she gets up to temp so I assumed that the two hoses on top of thermostat housing that go to the elbows one port and one starboard were after the thermostat. But only get water on plug once she gets to temp . Might be wasting time and money but I don't think it's the block but as I said not much else it can be

 

[Sparkey scott]

Ok scott06 it seems that I only get water at the transom ports when it gets up to temp on the guage and that is when I get water on #7 . Untill it gets to temp just have water coming from the prop . I may be wrong but I'm watching to make sure I have water flow . Again very new to this and any help is appreciated

 

[Sparkey scott]

Just a update. Replaced riser elbow and gaskets no water on #7 running on all 8 cylinders laketest tomorrow thanks all for the help hope I can be some help to someone else great forum keep up the great work thanks again all