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Old 15-03-2016, 09:57   #1
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3gm30f rebuild

I have pulled my engine and put it in my basement. Slowly taking it apart and marking everything. So far so good. Once broken down I will have the head and block looked at. No cylinder wall gouges but they are smooth with no cross hatching. I hope I can just go with new rings and a honing, but nothing ever goes as planned.

Well my question is I have all the bolt order and torque spec, but I can't find if I need to put anything on the head bolts first. Oil, antiseeze other?
Should all the bolts be replaced with new? Any helpful tips? I filled the cylinders with oil and after a week still level. But its been cool.
Any suggestions as to where to send the injector pump to? Thanks as always for your help and support.
Alan
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Old 15-03-2016, 10:16   #2
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Re: 3gm30f rebuild

I have an opinion, based on having rebuilt many engines over the years. No doubt others will have a differing opinion.

Head bolts should be very clean and dry when torqued in place. Done in the required pattern and in stages. The reasoning being that any type of lubrication will alter the amount of force applied by the torque wrench. It will be greater than indicated and possibly lead to problems, including stretching and weakening the bolts among others.

The torque spec can be derated to provide for the use of antiseize, or specified in the manual for the mandatory use of antiseize. Usually on aluminum blocks.

Over torquing can stretch the bolts so replacement may be indicated with careful examination.
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Old 15-03-2016, 10:28   #3
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Re: 3gm30f rebuild

If you don't have much ridge you should be able to go without boring etc. I was able to on that engine. Be sure to check your pistons closely for cracks, esp on the bottom ring groove and down. Never used anti seize, as noted make sure the bolts are nice and clean.
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Old 15-03-2016, 11:02   #4
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Re: 3gm30f rebuild

I'm guessing you have a service manual, but if not one can be located for download online.

Here's a pic for the sequence and torque values.


Edit,.... lol, I took two pics with my phone. One was sideways and one upright. So I uploaded the upright version and of course it's now sideways. When I worked in IT, I would have not slept until I figured out why. Glad those days are behind me now.
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Old 15-03-2016, 11:08   #5
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Re: 3gm30f rebuild

Light coat of 10w40 is what I was taught in college.
Anti seize increases torque applied so may strip bolts. If bolts are not "stretch type" should be fine to reuse them.,
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Old 15-03-2016, 11:23   #6
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Re: 3gm30f rebuild

Yes bolts can be reused, clean threads and a light oil on the threads is good enough prior to torquing. Oil / lube is required to keep the threads from binding as its torqued. I torgued the head bolts at 25, 50, 60 and 70 ftlb's.

It's good to sort all the bolts and washers into baggies marked with the assembly part. Makes it much easier when reassembling.
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Old 20-03-2016, 19:19   #7
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3gm30f rebuild

Clean threads on the bolts , installed with just a touch of oil, torqued in stages and run a tap through the bolt holes as well, blow out holes.
You can use the old ones provided they are in great condition.


Sent from SV Cloud Duster
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Old 20-03-2016, 21:00   #8
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Re: 3gm30f rebuild

Leave the bolts clean, no oil. Torque them carefully to the specified torque.

It used to be that manufacturers designed in lock washers to hold bolts down. Now, the bolts and their holes are designed so that when you torque a bolt to its designed torque, it stretches in its hole so that there's contact between the bolt and its threaded hole for the full length of the bolt. The friction of this bolt length contact holds the bolt in.

If you put oil on the bolt, and torque it to specs, it'll break. If it doesn't break you're doing something else wrong.

If the manufacturer specifies using oil or antiseize, then use it.
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Old 20-03-2016, 22:04   #9
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Re: 3gm30f rebuild

Consider taking your crankshaft and connecting rods to get them checked with magnaflux for micro cracks. $150 - 200 very well spent! My marina neighbor bought a 20 years old sailboat with a newly refurbished Yanmar 2GM20 engine. It looked and worked like new. After about 35 hours the connecting rod cracked, hitting crankshaft and making a hole in the crankcase. The rebuilder claimed it was a structural damage and not covered by repair warranty.

The owner managed to patch the dent in the crankcase by bolting together two thin steel plates, filled between with J-B Weld. This saved him the engine, but it still cost him $1200 to buy a new crankshaft, rod and bearings and a couple of weekends of labor to reassemble the engine. I am pretty sure the magnaflux check of the connecting rod would easily save him $1100 and huge frustration.
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Old 20-03-2016, 23:08   #10
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Re: 3gm30f rebuild

Quote:
Originally Posted by Seymore View Post
If you put oil on the bolt, and torque it to specs, it'll break. If it doesn't break you're doing something else wrong.

If the manufacturer specifies using oil or antiseize, then use it.
Might want the google that. Here's one link Perfect Engine Sealing Starts With Proper Head Bolt Use - Engine Builder Magazine

It's pretty standard practice to lube the threads of the head bolts, least with older cast iron blocks. If you don't oil or lube the threads the threads will stick / gaull and will prevent proper head torque.

As someone who learned from my dad and have several rebuilds under her belt including my 3gm30f with over 250 hours on it, I'm pretty sure I'm right.
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Old 21-03-2016, 04:26   #11
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Re: 3gm30f rebuild

Greetings and welcome aboard the CF, sstolo.
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Old 21-03-2016, 07:02   #12
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Re: 3gm30f rebuild

I will follow sailorchic's recommendations. From reading her posts she is concestantly on the mark. I have great respect of any of her comments. Thanks again sc
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Old 21-03-2016, 10:09   #13
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Re: 3gm30f rebuild

Sstolo, thanks for the recommendation. I'll follow up with that.
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Old 21-03-2016, 10:35   #14
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Re: 3gm30f rebuild

And I'm wrong yet again.

I think it's time for me to stop posting on the forum.
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Old 21-03-2016, 11:40   #15
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Re: 3gm30f rebuild

Never wrong
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