How important is precise torque on head gasket

[rednecktech00]

I have been through every so called marine mechanic in the area. All have made very expensive mistakes. So I found a guy on Craigslist advertising mobile boat service to replace the head gasket on my 2009 Mercruiser 3.0. I appreciated that he let me watch. I noticed he did not use a torque wrench for the head, valve cover, or manifold.

He seemed to really know what he was doing. I have been addicted to iboats forums for a long time. I'm fairly good at most things mechanical. Just wasn't interested in wasting what might have taken me weeks to do the job myself.

Should I go back in and torque everything to specs?

 

[Bondo]

Re: How important is precise torque on head gasket

Ayuh,.... Personally,.... I'd have torqued to spec the Head gasket,...

The other's get my calibrated elbow....

 

[Don S]

Re: How important is precise torque on head gasket

It's very important, especially on the 3.0L. They have had more than their share of head gasket problems. Did he by any chance use angle torque? It is a newer model, and all the V engines have gone to angle torque.

If he didn't use either, he's a hack and you shouldn't bother him again.

 

[rednecktech00]

Re: How important is precise torque on head gasket

Thanks Don and Bondo. I thought I had finally found someone I could count on. I am a computer guy by profession. Thinking about becoming a boat mechanic in retirement. I just can 't believe how much money I have given to so many idiots. I have found that most of the marine mechanics in central Illinois can't even get a driver's license.

 

[Eric 3.7LX Alpha 1]

Re: How important is precise torque on head gasket

I'm with Bondo, head would have been torqued down, in steps to final torque. Valve cover tightened with a 1/4" ratchet and socket by feel, and manifold by feel with a 3/8" ratchet.
The head... no way.

 

[rednecktech00]

Re: How important is precise torque on head gasket

Should I replace the gasket or just retorque?

 

[Don S]

Re: How important is precise torque on head gasket

If he over-torqued a few bolts, and you loosen them and retorque, it will probably leak.

Best bet is to use a new gasket.

 

[fat fanny]

Re: How important is precise torque on head gasket

If your smart enough o figure out this computer stuff you can do this! Get a merc manual and read it. just after the you get it back together and up to operating temp let it cool back to ambiant temp and re-check the torque in sequence. Believe me I have been through this a few times and this technique worked for me. And as mentioned above if it wasn't torqued with a wrench replace the gasket do it right and get rid of the mobile guy!

 

[rednecktech00]

Re: How important is precise torque on head gasket

If your smart enough o figure out this computer stuff you can do this! Get a merc manual and read it. just after the you get it back together and up to operating temp let it cool back to ambiant temp and re-check the torque in sequence. Believe me I have been through this a few times and this technique worked for me. And as mentioned above if it wasn't torqued with a wrench replace the gasket do it right and get rid of the mobile guy!

I really appreciate your words fat fanny.

I have read the merc manual. I'm just a bit intimidated by setting the valves. I'm sure there are lots of boat mechanics wishing they could do what I do. Here I am at work with my network running so well, I don't have anything else to do but read forums on iboats. I'm like the Maytag repairman here. Sick of my cubicle.

I really admire and envy you guys who are as sharp with engines as I am with network operating systems. Is there room in the boating industry for a guy like me?

 

[MarkSee]

Re: How important is precise torque on head gasket

with network operating systems. Is there room in the boating industry for a guy like me?

Yea, in Perth, Western Australia is where all the old IT guys go and become fabulous boat guys....I believe his name is.....Chris, see him.

Mark

BTW: I'm an OLD IT guys also:facepalm:

 

[joewithaboat]

Re: How important is precise torque on head gasket

I have been through every so called marine mechanic in the area. All have made very expensive mistakes. So I found a guy on Craigslist advertising mobile boat service to replace the head gasket on my 2009 Mercruiser 3.0. I appreciated that he let me watch. I noticed he did not use a torque wrench for the head, valve cover, or manifold.

He seemed to really know what he was doing. I have been addicted to iboats forums for a long time. I'm fairly good at most things mechanical. Just wasn't interested in wasting what might have taken me weeks to do the job myself.

Should I go back in and torque everything to specs?

Not all torque wrenches look the same. Some just look like an over-sized ratchet and have a twist handle with graduations on the barrel.

The head bolt torque is very important. I would just follow up to make sure they are tight enough. If you have not started it and gotten it hot, you might be OK. If they are over tight don't loosen them unless you plan to change the gaskets. Did he use sealer on the head bolts? If not id take them out one at a time and re torque them... again one at a time in the order the manual says.

 

[Struc]

Re: How important is precise torque on head gasket

I'm with Bondo, head would have been torqued down, in steps to final torque. Valve cover tightened with a 1/4" ratchet and socket by feel, and manifold by feel with a 3/8" ratchet.
The head... no way.

I'm a pretty seasoned mechanic (and computer guy), so logical, mechanical talents do cross boundaries. You can learn it.

But yeah, I'm with Eric and everyone else on this one. I've been doing engine work since I was 10, and pretty much torque everything by hand, EXCEPT the head. It's too important to be consistant.

That said, being able to torque by feel is something I do pretty well. I've even checked myself a few times and am usually within a few ft/lbs. Maybe he's just that good. I'd get a torque wrench and check the guy's work. Keep in mind the torque to get the head bolt moving will be higher than the actual torque of the bolt itself. Check them in the sequence in the manual. If he's low, torque it up to spec. If he's high on a couple, then torque all the rest of them to that spec and leave it. Unless he's like 15 ft/lbs too high, I wouldn't take it all back apart. If the spec is 75ft/lbs (I have no idea what the actual 3.0l spec is), and you find a couple up near 85ft/lbs - go through and torque all to 85 ft/lbs and run it. It's important to have a consistant torque more than an exact spec. I tend to torque a little past spec on the head as a common practice anyway, and have never had issues. WAY over spec can warp or distort things - so in that case, I'd take everyone's advice and take it apart and replace the head gasket and do it again.

Take my advice for what it's worth... I'm one guy out of millions - just my opinion on what I would do.

 

[Bondo]

Re: How important is precise torque on head gasket

Originally Posted by Eric 3.7LX Alpha 1
I'm with Bondo, head would have been torqued down, in steps to final torque. Valve cover tightened with a 1/4" ratchet and socket by feel, and manifold by feel with a 3/8" ratchet.
The head... no way.

I'm a pretty seasoned mechanic (and computer guy), so logical, mechanical talents do cross boundaries. You can learn it.

But yeah, I'm with Eric and everyone else on this one. I've been doing engine work since I was 10, and pretty much torque everything by hand, EXCEPT the head. It's too important to be consistant.

That said, being able to torque by feel is something I do pretty well. I've even checked myself a few times and am usually within a few ft/lbs. Maybe he's just that good. I'd get a torque wrench and check the guy's work. Keep in mind the torque to get the head bolt moving will be higher than the actual torque of the bolt itself. Check them in the sequence in the manual. If he's low, torque it up to spec. If he's high on a couple, then torque all the rest of them to that spec and leave it. Unless he's like 15 ft/lbs too high, I wouldn't take it all back apart. If the spec is 75ft/lbs (I have no idea what the actual 3.0l spec is), and you find a couple up near 85ft/lbs - go through and torque all to 85 ft/lbs and run it. It's important to have a consistant torque more than an exact spec. I tend to torque a little past spec on the head as a common practice anyway, and have never had issues. WAY over spec can warp or distort things - so in that case, I'd take everyone's advice and take it apart and replace the head gasket and do it again.

Take my advice for what it's worth... I'm one guy out of millions - just my opinion on what I would do.

Ayuh,..... 10, huh,.... Late bloomer,..??.....

I think I had a 9/16" end-wrench, insteada a baby rattle......

 

[mnypitboat]

Re: How important is precise torque on head gasket

I am with everyone else. I skimmed through all the responses. Not sure if anyone mentioned it, but one reason for torquing the head is warpage. There is not just a torque spec, but also an order to which to torque first and last. It is absolutely essential that you torque the head. There could be mixed opinions on the rest, but the head is essential.

That being said, If it were mine, I would try the retorque method, but expect failure. Just in case the guy had a pretty good "feel" for torque, you might get lucky, and you dont want to do extra work if it is not necessary.

 

[rednecktech00]

Re: How important is precise torque on head gasket

Not all torque wrenches look the same. Some just look like an over-sized ratchet and have a twist handle with graduations on the barrel.

The head bolt torque is very important. I would just follow up to make sure they are tight enough. If you have not started it and gotten it hot, you might be OK. If they are over tight don't loosen them unless you plan to change the gaskets. Did he use sealer on the head bolts? If not id take them out one at a time and re torque them... again one at a time in the order the manual says.

He did use sealer. I didn't want to say anything because I have already been through every mechanic in the area. It bothers me though. I will probably pull it apart. I do enjoy working on it. Right now, I am building a cart to pull my outdrive for the first time. Also have some electrical I want to explore. I almost enjoy working on it as much as I enjoy running it.

 

[rednecktech00]

Re: How important is precise torque on head gasket

I am with everyone else. I skimmed through all the responses. Not sure if anyone mentioned it, but one reason for torquing the head is warpage. There is not just a torque spec, but also an order to which to torque first and last. It is absolutely essential that you torque the head. There could be mixed opinions on the rest, but the head is essential.

That being said, If it were mine, I would try the retorque method, but expect failure. Just in case the guy had a pretty good "feel" for torque, you might get lucky, and you dont want to do extra work if it is not necessary.

I was watching the order. He did that right.

 

[Struc]

Re: How important is precise torque on head gasket

Ayuh,..... 10, huh,.... Late bloomer,..??.....
I think I had a 9/16" end-wrench, insteada a baby rattle......

Yeah - my dad had a lake weed cutting business in the summer, and snow plowing in the winter. We had tons of vehicles, and they all needed work done. I never had a chance to escape.

 

[ENSIGN]

Re: How important is precise torque on head gasket

I'll second that

Ayuh,.... Personally,.... I'd have torqued to spec the Head gasket,...
I'll second that
The other's get my calibrated elbow....

 

[spdracr39]

Re: How important is precise torque on head gasket

Seems to be a consensus here. Now that's unusual

 

[artificialreef]

Re: How important is precise torque on head gasket

Hi redneck, i am a networking it schlub too. I had some jobs in the mechanic biz when i was younger, (machine shop and r&r) I learned the hard way on one of my vehicles that a head gasket job i did failed when i did 2 mistakes. 1. i bought a cheap harbor freight torque wrench, (spend the money on a good one if you plan to have this as a hobby) prob that angle one don mentioned by a good brand. He may recommend one. 2. I didnt chase/clean out the bolt holes with a thread chaser. Blow them out with compressed air. When you are scraping the old gasket off its easy to get stuff in the holes and that does not help your torqueing. Dont know if the marine mech pro's here recommend chasing the threads. I just do it on land motors. Maybe they will chime in. I cant find a good (auto) mech down here in fl. Every time i had something done it went bad in short order. Then when i went back to fix the "pros" job i found bolts missing, and things not connected. I do everything i can myself now. There are most definately great mechs out there. Alot are on here. Good luck, welcome and enjoy your new hobby. Oh yeah i always have the head magnafluxed (for cracks, aluminum is another method)and checked with a straight edge and feeler gauge for trueness before reassembly. Your even supposed to check the block deck surface. I was never a big fan of just pulling it off then putting it back on though alot of folks do it. It costs a little green at the machine shop to have checked but remember this is a marine engine. This might sound dorky but i look at it sort of like going into space. Do you really want to cut corners?