PDA

View Full Version : leaky manifold ??


rob935
06-21-2009, 10:29 AM
hi guys , my motor (93 prostar 351 indmar) started to run rough and put out white coloured water out the exhaust :confused:2 weeks ago , i put it down to bad/ dirty fuel so i drained and cleaned the tank put new plugs and filters in but no change !! theres water getting in to the fuel mix somehow , i think it may be a faulty manifold any ideas ?? i some how doubt its the head gaskets as its never overheated and the oil is still clean with no sign of water mixed in ..:confused::(

BriEOD
06-21-2009, 11:08 AM
I had an after market Edelbrock intake manifold on my 87. The water jacket eventually started getting some pitting/degradation which allowed water to seep past it. Granted, it was aluminum not heavy metal. You'll have to take your exhaust manifolds off to remove the intake manifold.

JimN
06-21-2009, 11:42 AM
hi guys , my motor (93 prostar 351 indmar) started to run rough and put out white coloured water out the exhaust :confused:2 weeks ago , i put it down to bad/ dirty fuel so i drained and cleaned the tank put new plugs and filters in but no change !! theres water getting in to the fuel mix somehow , i think it may be a faulty manifold any ideas ?? i some how doubt its the head gaskets as its never overheated and the oil is still clean with no sign of water mixed in ..:confused::(

Could be a bad head gasket, too. It's not necessary to overheat it for that to go bad. Check your compression and vacuum. If they're normal, it could be a bad exhaust manifold, too.

Have you run it on the trailer?

rob935
06-21-2009, 03:39 PM
sorry guys when i said manifold i meant to say exhaust manifold , im just wondering if this is cracked internally would this lead to water getting into the cylinders ,

TMCNo1
06-21-2009, 04:17 PM
sorry guys when i said manifold i meant to say exhaust manifold , im just wondering if this is cracked internally would this lead to water getting into the cylinders ,

It is quite possible if the manifold/riser is leaking, that water could get into a cylinder, remember water doesn't compress and it can hydraulic it and bend a rod, crack the cylinder wall, break a crankshaft and then your into big $ for a engine rebuild/replacement.
I know JimN will elaborate better than I.

JimN
06-21-2009, 11:02 PM
It is quite possible if the manifold/riser is leaking, that water could get into a cylinder, remember water doesn't compress and it can hydraulic it and bend a rod, crack the cylinder wall, break a crankshaft and then your into big $ for a engine rebuild/replacement.
I know JimN will elaborate better than I.

The good thing is that parts are easily available for these motors and they're pretty easy to work on, if the worst happens.

I would look at the exhaust manifolds first- they're the easiest place to start.

maristar 240 dave
06-22-2009, 12:42 AM
here are some new manifolds that were just installed on my Maristar 240. I had a lot of steam coming out of one side of the exhaust. Pulled the exhaust manifold and one of the holes had rust in it and must have been leaking. These are expensive parts. Total for both manifolds and risers was a grand.

48603

48604

rob935
06-22-2009, 05:25 AM
thanks lads , excellent feed back as always, just a question for jimN if the exhaust manifold was the problem and i was to give the boat a quick run on the trailor in theory would it run ok or do i need to strip the head down to see if theres water in it first ....im quite sure its the manifold but im trying to do a pin point diagnosis before i splash out on the fix . thanks again .

JimN
06-22-2009, 09:10 AM
thanks lads , excellent feed back as always, just a question for jimN if the exhaust manifold was the problem and i was to give the boat a quick run on the trailor in theory would it run ok or do i need to strip the head down to see if theres water in it first ....im quite sure its the manifold but im trying to do a pin point diagnosis before i splash out on the fix . thanks again .

If you think the manifolds are the cause, pull them and inspect them. It's not as if you'd be tearing the motor apart and they go back on pretty easily so it would be the logical first step.

rob935
06-23-2009, 05:03 PM
just back from the lake .....put boat on the trailor pulled the manifolds and did a compression test , 7 pots are fine but number 5 is ten percent lower than the rest and has oil oozing out of the same exhaust port , will i assume the head gasket is the problem now ??

JimN
06-23-2009, 10:52 PM
just back from the lake .....put boat on the trailor pulled the manifolds and did a compression test , 7 pots are fine but number 5 is ten percent lower than the rest and has oil oozing out of the same exhaust port , will i assume the head gasket is the problem now ??

Sounds like it. If you can get a vacuum gauge, test for that, too.