A high mileage LQ1 thread

[rich_e777]

So I pulled this thing out because reaching over it to fix the heater hose at the firewall was a pain in my back, and for fun. Mostly fun, Well dropped the front subframe and rolled it out with the trans but its out and on the stand. The patient is a 1995 LQ1 that has 257K miles on it and well maintained by the previous owner. But it was experiencing some high mileage issues such as seeping gaskets, a bad valve stem seal, could use a new timing belt and probably a few other things. 

Before I really get any further into the engine I`m gathering tools, parts and advice as to what I should replace while apart. The plan was to get the heads off to a shop to be rebuilt and planed if needed, change the oil pan gasket which was completed and she got a new oil pump, replace all the gaskets and seals while accessible like the front/rear main seals and timing cover gasket in addition to what would be replaced with the head job. I dont know if I need to even mess with anything below the heads so I`m not sure if I should look into a complete engine rebuild or not given the mileage. 

Heres a close up of the current timing belt and actuator area, 80% of it looks this way and iirc Dan said it had about 20-25k on it when he sold it to me back in `16. I put maybe 2k on it til it was parked. There was some dust from the belt but not a huge build up.

Well pics arent working like they used to. Figuring it out...

 

 

Edited December 28, 2021 by rich_e777
Direct Link from Imgur, forum auto embeds now!

[94 olds vert]

I think I got the pictures figured out. 

 

[GTP091]

Head over to rock auto and get a gasket kit for the engine. You’ll want ‘cylinder  head gasket kit’ not to pricey. as for the bottom end you’ll want to do a compression test to test it out 

[rich_e777]

Sweet, as did I. Threads are useless without pics right? 

 

I did make a preliminary visit to RA and have the Victor Rienz HG set (has 2 orings or seals the felpro didnt), new Tstat, AC Delco spark plugs, water pump with correct impeller design, knock sensor. as well as other stuff under the hood not pertaining to the engine. RA has been awesome so far.

Ah compression test good idea, I`ll set up to do that today. Sounds like fun.

Thoughts on torque wrenches? Ive got an old Sears beam style Ive used for years to get by but never gone into an engine with it past the lower manifold. Would a click type be better to use or is the one I have ok?

 

 

[94 olds vert]

33 minutes ago, rich_e777 said:

Sweet, as did I. Threads are useless without pics right? 

 

I did make a preliminary visit to RA and have the Victor Rienz HG set (has 2 orings or seals the felpro didnt), new Tstat, AC Delco spark plugs, water pump with correct impeller design, knock sensor. as well as other stuff under the hood not pertaining to the engine. RA has been awesome so far.

Ah compression test good idea, I`ll set up to do that today. Sounds like fun.

Thoughts on torque wrenches? Ive got an old Sears beam style Ive used for years to get by but never gone into an engine with it past the lower manifold. Would a click type be better to use or is the one I have ok?

 

 

I rebuilt my cub engine with an old sears one like you have. Seems to work just fine being from the 1970s or 1980s. 

It might be worthile to upgrade to a modern one since this engine is a bit more complex. 

Look up the old double gasket for the oil sump. It'd be a good idea to do that as these engines like to leak oil from that spot. 

[rich_e777]

Ah I remember reading about that years ago, DDG pulled the old thread right up.

Crazy K posted the LQ1 specific info on the second page. P/N 10477565 for brown O-ring and a paper distributor gasket from anything from the 80`s V6 Chevy lineup.

[Schurkey]

13 hours ago, rich_e777 said:

Ah I remember reading about that years ago, DDG pulled the old thread right up.

Crazy K posted the LQ1 specific info on the second page. P/N 10477565 for brown O-ring and a paper distributor gasket from anything from the 80`s V6 Chevy lineup.

That thread calls the O-ring "silicone", which is wrong.  It's Viton.

http://hbassociates.us/Lumina_Oil_Pump_Drive_01.JPG

 

[Schurkey]

On 12/27/2021 at 4:49 PM, rich_e777 said:

1995 LQ1 that has 257K miles on it and well maintained by the previous owner...

...Before I really get any further into the engine I`m gathering tools, parts and advice as to what I should replace while apart. The plan was to get the heads off to a shop to be rebuilt and planed if needed

Inspect the head gaskets closely. There's a weak-spot on the cylinder heads near #1 and #6, the heads distort, and the head gasket pops.  When it does, it tends to scuff the iron block.  I had a shop cut .015 from the heads to clean them up.

http://hbassociates.us/Lumina_Head_Gasket_02.jpg

http://hbassociates.us/Lumina_Head_Gasket_03.jpg

Verify the timing chain and the plastic guides.  Everyone talks about the timing belt, but if the engine is apart anyway, you'd better have a look at the chain and it's tensioner.

The exhaust valves get beaten-up pretty badly.  The seats are hardened inserts; and they seem to hold up very well--but the exhaust valves look terrible.  Intake valves and seats seem to hold up pretty well, as do the guides--but have the machine shop check everything.  I ground my exhaust valves about .003--.005 and they cleaned-up nicely.  Intakes cleaned-up at .001.

Fresh-ground, and untouched used exhaust valves:

http://hbassociates.us/Lumina_Valves_01.jpg

A '95 engine may--or may not--have the updated camshaft/lifter oiling update.  There was a service bulletin about that, with a parts "kit" that was long-ago discontinued.  The only thing in the parts kit that was "special" was the new, slightly-thinner thrust plates for the camshafts.  The other parts were gaskets, set screws, cup plugs--stuff you could source outside of GM.  You could have your existing thrust plates shaved by your favorite machine shop.  They need to make them a few thousandths thinner.  If your soft plugs at the end of the camshaft are solid, you should perform the update.  If the soft plugs have a small hole in the center, the update has already been done.

http://hbassociates.us/Lumina_Cam_Bulletin_001.JPG

http://hbassociates.us/Lumina_Cam_Bulletin_011.JPG

 

Edited December 30, 2021 by Schurkey

[Schurkey]

Oh, yeah.  (With the engine in the vehicle) When the rear cylinder head and cam-carrier are removed, it's E-A-S-Y to install a fresh alternator and a block heater.  Maybe even consider a fresh crank sensor.

Be sure you have the CORRECT block heater, if you're inclined to install one.  The KATS / Five Star block heater listed for 3.4 DOHC does NOT fit.  Buy the Zerostart / Temro heater instead.

http://hbassociates.us/Lumina_Block_Heater_01.jpg

http://hbassociates.us/Lumina_Block_Heater_03.jpg

Edited December 30, 2021 by Schurkey

[jman093]

A clicker-type torque wrench is going to be way better than a beam.

I've had apart a couple high-mileage LQ1s and as Schurkey has said, you'll probably find the valves need work.

I would also second replacing the oil pump drive gasket whether it needs it or not since it's only accessible with the head off.

You mentioned you know it needs valve stem seals. I bet if you look closely at the heads when they're off, you will find some valve guides have sunk into the ports, particularly the exhaust ones, which get much hotter than the intake. It's a big problem on the LQ1. It gets diagnosed as bad valve stem seals, but in reality the problem is the seals are just riding up and down with the valve since they aren't affixed (or aren't affixed well) to the guide. Any sunken guides will need replaced. When apart, I have always put snap rings all my guides, whether they're new or reused ones, before assembling so that they will never sink down into the head. You'll need a special tool to cut the groove in the guides for the snap ring, but a cylinder head machine shop should be able to do that for you.

The bottom end of an LQ1 is stout they they last a long time with maintenance. My DD 96 Z34 is up 230k and runs great.

Edited January 1, 2022 by jman093

[55trucker]

At 260,000 miles personally I wouldn't do anything to tighten up the top end without giving the bottom end a careful consideration as to what condition the bearing clearances are, the condition of the bearings themselves (given the era the bearing will be tri-metal), expect to see the outer coating worn away & the copper inner layer exposed, & what condition both the main & rod journals are in, one doesn't want to see grooves ground into the journals nor them being out-of-round. One should plasti-gage everything to inspect all the clearances.

Replacing the oil pump is a decent route to take but the pump can't overcome loosened up clearances. The intermediate shaft bearing clearances are a little more involved.

Then there's looking at the condition of the cylinder walls.........

[Schurkey]

On 1/1/2022 at 1:50 PM, jman093 said:

A clicker-type torque wrench is going to be way better than a beam.

A QUALITY click-type torque wrench is good for achieving torque.  In other words, "assembly".  Shiity bottom-feeder Asian junk is to be avoided.  Decent torque wrenches are readily available from USA manufacturers under several brand names sold by a multitude of retailers including Amazon.  CDI and Precision Instruments are two I'd recommend, but there are others.  Torque wrenches EXCEPT for deflecting-beam type need to be sent out for verification/calibration periodically;  the two companies I've personally dealt with are

www.anglerepair.com

www.teamtorque.com

Both companies charge more for electronic torque tools than simple "clickers".  That's one reason I don't own electronic torque wrenches.

 

A deflecting-beam torque wrench is best for TESTING torque--not assembling, but verifying afterwards.  Deflecting-beam torque wrenches are inherently accurate in their mechanism, but chock-full of user error.  (They're difficult to use correctly.  Generally, they have no ratchet which is a pain in the ass.  Hand position on the handle affects the reading, not looking at the pointer/scale "square" affects the reading, arm-shake from trying to hold high torque for a long time affects the reading...you get the idea.)

Edited January 3, 2022 by Schurkey

[rich_e777]

Hey I appreciate the replies and info. Awesome stuff to know about the valve guides, RA has them so I`m tempted to grab them while in stock. The timing chain was something else I had anticipated changing but Ive not ordered one yet. Some engines I heard they stretch a little and it throws the timing off. 

I have my compression and leak down kits now and will order a torque wrench and plasti-gauge set. I can understand how to use the plasti gauges but is there a section in the FSM that lists all the places you`d want to use on?

[pwmin]

might help if you're shopping for a click torque wrench

 

[55trucker]

7 hours ago, rich_e777 said:

I can understand how to use the plasti gauges but is there a section in the FSM that lists all the places you`d want to use on?

Plasti-gauge is available in 3 different gauges.......green for .001 (1 thou) to .003 ( 3 thou), red is for .002 ( 2 thou) to .004 (4 thou)

green is what you want to use.

One has to completely dry off all the main & rod journal surfaces, individually remove the bearings from the caps & rods/block to clean everything & then dry them off. Because the block is still assembled one backs off the bolts on both all of the main & rod caps,tap the caps free, starting with the mains one slips out the cap side of the bearing then slides out the block side of the main bearing individually ( not all together). Dry each one off then slide the block side back into place around the journal & slip the cap side back into place. Cut a small section of the plasti-gauge less than the width of the journal, with the cap off lay the section across the width of the main journal. Do them all in this manner, when you have done all the journals put the caps back into place and without moving the crank torque all of the mains back down to spec. When all are torqued then back off the bolts again to remove the caps. With the plasti-gauge sheet place the calibrated gauge against each journal & accurately check which reading corresponds to what the thickness of each crushed plastic section is...that is what the clearance is.

The ideal clearance on both main & rod is .0015 (one & a half thou), the GM manual will state that max clearance is 3 thou but from personal experience 3 thou is too loose to allow the oil pump to hold proper pressure when the engine is hot & at idle. The last bottom end I did on a 3400 we turned the crank & resized the rods to allow the rod & main clearances at .00175 thou.

Of course if the crank journals are scarred then this all mute, the crank will need turning & resizing the rods would be in order.   

 

Edited January 4, 2022 by 55trucker

[Schurkey]

4 hours ago, pwmin said:

might help if you're shopping for a click torque wrench

 

That video proves that a person doesn't have to have any sense to make a Youtube video.  He buys a "precision" torque tester, then bolts it to a piece of wood that flops all over, ruining any hope of accuracy.

[pwmin]

Yeah, I did notice that.  He's usually good with setting up testing rigs.