mercruiser 165 manifold issues

I've searched the other posts and I'm pretty sure I know what's wrong with my friends 165. The exhaust manifold might be cracked and water is getting into the engine. could also be the block and head gasket too so we're gonna get the manifold pressure tested first.<br /><br />This is like the 3rd manifold he's had to do on this engine.<br />The first time it was cracked and then the replacement was defective so hence another. After 4 months of great running it started all over again. Oil foam spewing out the PCV and oil is milky and gross.<br /><br />Does anyone know if this engine has a problem with cracking manifolds? Why would this keep happening? The new manifold was torqued using the proper sequence and amount shown in the shop manual. We are hoping it isn't cracked again.<br /><br />Thanks for any insight into why this keeps happening.<br /><br />Jeff

Re: mercruiser 165 manifold issues

could it be freezing? Is it cold enough in BC this time of year, say night time temp down to 20F?

Re: mercruiser 165 manifold issues

Skinsk has it on the nose. Have you been winterizing the engine. ie draining the manifold?<br /><br />There is always water to come out of them...even if you turn the Petcock, and nothing comes out..remove the petcock and stick a wire in. Water needs to be removed.<br /><br />TMD

Re: mercruiser 165 manifold issues

Thanks for the replies. I live on the west coast of BC. Vancouver Island.<br />This boat is used year round to commute. It rarely gets cold enough here to freeze and when it does it doesn't last long.<br />Certainly at this time of year we are far away from any freezing. This manifold was put on only 4 months ago and now it may be cracked again.<br />tia<br />Jeff

Re: mercruiser 165 manifold issues

Jam is motor the 250 cid inline 6 cylinder or the 3.7 inline 4 with cloosed cooling and 2bbl carb (otherwise refereed to as 470) both of these motors were rated at 165hp range, anyway if you can provide which engine and year I might be able to give up some info...I have lots wrenching time with the 3.7 4 banger,and I'm currently working a manifold, overheating issue.

Re: mercruiser 165 manifold issues

One other thing also.....Was the riser changed?

Re: mercruiser 165 manifold issues

This motor is the 250 cid inline 6.<br /><br />And to answer Trent's question, no I don't believe the riser was changed. Should it be?<br /><br />Thanks<br /><br />Jeff

Re: mercruiser 165 manifold issues

It is possible that you have a small crack in the block..probebly happend when the original manifold cracked.<br /><br />TMD

Re: mercruiser 165 manifold issues

Yes, It should be changed. Down here risers and manifolds only last four or five years if in saltwater. Normally a riser will go before the manifold in saltwater. Freshwater engines will last many years. That is a bulletproof engine and I personally have never seen so many manifolds changed. Change the riser with new gaskets. You could have the old one pressure checked. Cracked riser will let water get into the block after shutdown. As was said, I hope the block is not cracked.

Re: mercruiser 165 manifold issues

Thanks for the replies.<br /><br />The manifold is off now and looks cracked. Pressure test will be today, if cracked, hopefully under warranty still, since it's still new.<br /><br />How can you tell if the block is cracked? There is a replacement engine for this. It might be an idea to put that one in and see what happens. This engine is getting tired anyway.<br /><br />Will have a look at riser too.<br /><br />Jeff

Re: mercruiser 165 manifold issues

ok, I have an update.<br /><br />The manifold was taken to the wholesaler where the manifold was purchased by the dealer. It was definitely cracked. Easy to see the crack. The guy asked me if I had installed a "reverse flow". Apparently the thing doesn't cool evenly unless you put this "reverse flow" thing on it. <br />A Mercruiser defect? The engine was apparently recalled. SO, if you put a new manifold on it will do it again and again without the reverse flow thing. <br /><br />So at this point I am not even sure what a "reverse flow" adaptor is or if it's still available. Does anyone know? The dealer, who installed the manifold the first and second time said nothing about this! Now, guess what, they are out of business....<br /><br />Thanks for any insight into this "reverse flow" adaptor, if there is such a thing.<br /><br />Jeff

Re: mercruiser 165 manifold issues

This is where I call B.S!!<br />Never heard of such a thing. I looked at the current parts breakdown and nothing. Look at exhaust kits from other makers of manifolds (nothing is said about a "reverse flow") My service bullitins only go back to 1988 and nothing is listed. The only thing I could think of that he might be talking about is the exhaust shutter which was standard. And its located here....<br /> <br />Its item #7. It should be checked to make sure its still their. They do need replacement every now and then. What brand manifold are you using? Barr, Osco?? Iv heard of some problem with Osco over the years but never had one personally.

Re: mercruiser 165 manifold issues

Again, thanks for the replies.<br /><br />I failed to mention that this is a 1971 boat/motor etc. so I apologize for that.<br /><br />Here is the information we have found and if anyone else is having this problem the information is here for you too.<br /><br />Begin Service Bulletin No. 83-19<br />Exhaust Manifold Water Reversal Kit – MCM 165<br />Under certain operating conditions, the exhaust manifold can develop an internal crack in the water<br />jacket. This crack is usually in #2 or #3 exhaust port. If this condition is experienced, install Water<br />Reversal Kit Part No. 60252A3. This kit reverses the water flow thru the exhaust manifold. Water<br />(from the engine) enters the rear manifold end cap and flows forward. The water exits the manifold from the front end cap and flows (via a hose) to the exhaust elbow. Follow instructions, that come with kit, for installation.<br />Water Reversal Kit 60252A3<br />End service bulletin <br /><br />We were able to find a kit for $175 cdn. + $600 for the manifold (at cost).<br /><br />It's too bad my friend was screwed by that company, now out of business. Buyer beware I suppose.<br /><br />Thanks for all the help, this is a great forum.<br /><br />Jeff

Re: mercruiser 165 manifold issues

I also own an early model Mercruiser 165 IL6. Has anyone else heard of such a problem? The only thing I have heard regarding this motor is that it is so reliable!

Re: mercruiser 165 manifold issues

FreeBeeTony,<br /><br />This is only a fix as per the service bulletin if recurring cracked manifolds (like my friends boat) is a problem.<br /><br />This will be the 3rd manifold in under a year for this boat so something was causing it and in so far as I can see, the service bulletin addresses the cause.<br /><br />Jeff

Re: mercruiser 165 manifold issues

Pssst!......<br /><br />Don't overlook your water temp guage and sensor. <br /><br />If it's giving you false readings it would be completly normal to crack one manifold after another running along thinking you are all set, yet the engine is constantly overheating on you.<br /><br />Just thought I'd mention that..<br /><br />Good luck!