Does anyone have the torque specs handy for the lower intake manifold bolts? Sequence? Any tricks or tips for doing this on a 98 that I should know?
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02-08-2012
Does anyone have the torque specs handy for the lower intake manifold bolts? Sequence? Any tricks or tips for doing this on a 98 that I should know?
02-08-2012
Don't torque them.
I mean if you want to snap the head off all the bolts you can.
Just start bolting them down and just pick random ones and go till they are all snug + a little.
The torque spec will break them, same with UIM bolts and supercharger bolts, just snug and a little more.
02-08-2012
??????
You're kidding right?
I've done numerous LIM gaskets on 3100, 3400, and 4.3L engines and the torque spec is crucial!! I have not done a 3800, but assume it's similar?
02-08-2012
never torqued a 3.1 3.4 or 3.8 and no leaks ever.
02-08-2012
Nope, not kidding, ive never once torqued anything on the top half of these motors, the only thing I would, would be the head bolts.
Go snug + some and your golden.
Make sure you got rtv in the 4 corners for the LIM where it meets the block or it will leak.
02-08-2012
I do the 11ft/lbs. That was with a digital torque wrench from snap on... And no i didn't spend the money for it haha
02-08-2012
Originally Posted by TheOtherNick
Wow, you've got more balls than I do! I personally don't like doing these jobs more than once so I always go by the book.
02-08-2012
Im an auto tech, so after a while you get a feel for how tight things go.
02-08-2012
Lol yeahh. Most stuff you can feel it. Heads, rockers and lim is torque
02-08-2012
Well, that does make a difference then.
02-09-2012
For someone that doesn't wrench everyday...a torque spec keeps them consistent.
LIM when the plastic gasket didn't have metal spacers was spec'd at 11ft lbs
LIm once the plastic gasket had metal spacers to keep it from getting crushed was spec'd at 13ft lbs
I personally torque the aluminum gaskets to 15ft lbs as they are a better design and there's no worries. I've done probably 100 of them and never had one issue.
TIP: ensure you put some sealant on the lim bolts. They are in oil and coolant passages and will seep fluid over time onto the LIM if you don't seal them.
Tip2: The LIM bolts are 3/8", if you use a 10mm likely you'll round the heads when torquing.
SC bolts, factory spec is 17ft lbs. I typically use 20ft lbs.
I've never stripped/broken one of these bolts with the above specs.
02-12-2012
Thank you Bill! Those are the numbers I was looking for.
02-12-2012
Also, thanks for the two tips. I remember hearing about sealing the bolts. This is different than the 3100 and 3400 engines where you are supposed to use threadlocker to help the bolts hold tight with the lower torque specs correct? A person should use the white thread sealant...?
02-12-2012
I always use red locktite when doing 31/3400 lim
02-12-2012
I have always used some type of thread sealant, and the white sealant works well. I would not use loctite, it is used to hold bolts not seal them and with the 3.8 you need to seal them. I have done it this way too many time to count and have not had any issues.
02-12-2012
Have any of you personally seen coolant and/or oil seep onto the LIM from the bolts?
I personally just do not see how oil is going to work against gravity and travel 4 inches up the length of the bolts and get all over the manifold. I recently assisted a LIM on a 3.4 engine, and there was a little oil on the threads of the bolts, but no where near the head of the bolt.
For everyone using loctite on these bolts, the threads are already pre coated in loctite, just like your wheel bearing bolts.
02-13-2012
I sure have. It'll seep slow.. along the lines of how if you touch a paper towel hanging over a glass of water, the water will travel up the towel. Coolant is more likely as it's under pressure.....I have seen both though.
Technically the GM FSM somewhere or a tech bulletin states to use locktite. I've never and prefer the sealant as well. Learned it from a GM Tech who is a buddy.
02-13-2012
Yes, thread sealant it will be for sure.
Threadlock only on the 3100 and 3400 engines.
Bjorn - From what I understand the 3100 and 3400 lower intakes are slightly different than the 3800 in respect to the lower manifold bolts. The 3100 and 3400 are dead holes, do not have the oil/coolant passages behind them... Correct me if I am wrong.
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