Engine blueprints needed

[andy6374]

Without going into how I got to where I am now...<br /><br />I have an 88' V6 200hp.<br /><br />I have to retap or rethread the 4 bolt holes for the pressure relief valve. The holes are stripped out to the point that heli-coils aren't an option anymore. Will probably have to go up to 3/8 from 5/16. But in an attempt to keep it the factory 5/16 a machinist and I were thinking of drilling the holes a bit further and try to get some of the heli-coil to bite. Here's the question, how much more metal is there behind the already tapped holes. I don't want to drill to far.<br /><br />-Thanks<br />Andy

 

[Laddies]

Re: Engine blueprints needed

andy, don't know were you could get that answer other than the factory, but we have had simular problems fixed by a local shop with a TIG welder they clean and weld the holes, drill and retap them, the bad thing is you have to remove the powerhead for them

 

[Nos4r2]

Re: Engine blueprints needed

Try these instead? they are quite a bit bigger diameter than helicoils-just make sure they can't come out.<br /><br /> http://www.timesert.com/

 

[andy6374]

Re: Engine blueprints needed

Thanks guys-<br /><br />Nos4r2, I contacted the people at timesert and told them of my situation. My concern is that the holes might already be to large for the 5/16-18 insert...we will see. However, they are closed down until Jan. 3, so I won't know for a little bit.<br /><br />Laddies, I figured the machine shop answer would require removing the powerhead...not what I was hoping for. The engine was rebuilt two years ago so perhaps getting the mounting bolts out won't be too bad.<br /><br />This seems like a real shady situation I've gotten myself into. It is very annoying because even though the relief valve is necessary, it isn't the heart of the engine. I've got nice even compression and the thing runs like a champ and this stupid mess-up might cost me big.<br /><br />This may a real stupid question: Do they make studs that are half one size and half another. Like one end 5/16 and the other 3/8, that would be too perfect .

 

[Chinewalker]

Re: Engine blueprints needed

Hi Andy,<br /> There's absolutely no reason why you can't make some studs like that. A machinist could probably turn down some stock on a lathe and run a die on either end to make what you need. Seems like it should work to me....<br /><br />- Scott

 

[andy6374]

Re: Engine blueprints needed

Alright I was just contacted via phone by Mercury Marine. They said DO NOT drill any further. And they recommended to weld the holes and retap, as Laddies mentioned. I told them about my concern about the powerhead mounting bolts breaking and thus more trouble. He proceeded to tell me that any good machine shop (or least the ones in his area) would repair those holes without powerhead removal.<br /><br />I mentioned the two-sided stud idea and they said "Well, uh...you could, but I really think the way to go is..." (what he mentioned before).<br /><br />Now I just have to find the machine shop. Anybody know any good ones in RI.<br /><br />-Thanks<br />Andy

 

[andy6374]

Re: Engine blueprints needed

Can you guys imagine the system without a poppet valve? The guy who rebuilt the engine, when I just called him said "you got a 88' V6 Black Max from me with a poppet valve, damm I screwed you". He claims they don't need them and that he removes them on every rebuild and that Black Max's can take as much cooling water as you can give em'. I really trust the guy, he's a stand up mechanic, stand's by his work, has given free used parts, walks me through things over the phone. But I really want a second opinion. I trust you guys too.<br /><br />How can it run without it. I mean if you plug up the hole in which the carrier, grommet, and poppet sit...won't it overheat a higher RPM's. And if you just seal up the area in which the relief valve plate sits, won't all the water empty into the exhaust at idle and thus overheat.

 

[paulie0735]

Re: Engine blueprints needed

Sounds like you have a few options to go forward with. I would go the stepped stud option, any good machine shop could make you a set with any thread combination you want, worth trying before you pull the thing down and have it welded up.

 

[Laddies]

Re: Engine blueprints needed

Andy, if Mercury could get away with out a poppet valve or for that matter anything else to save a buck they would not have spent the money to put it in the engine in the first place--Bob

 

[andy6374]

Re: Engine blueprints needed

As usual Laddies, you are right to the obvious point and I agree. But just wanted the opinion on how it could run without it (which I guess you gave me).<br /><br />I will try the stepped stud as a first measure, then I will see the wrench and machine shop.

 

[Nos4r2]

Re: Engine blueprints needed

Just a thought-is it possible to open up the boltholes on the cover to take a larger thread for the entire stud? I've come across stepped studs a couple of times on motorcycle exhausts and they break quite easily at the step. They usually have part of the bigger diameter thread or a blank part of the thicker part of the stud exposed to facilitate removal when this happens-as below.<br /><br />

 

[paulie0735]

Re: Engine blueprints needed

If you go with the step studs make sure they are from good quality stainless and use a thread release compound when installing them.