New to the lq1

[tunerz34]

Hi Im new to the lq1 motor Ive heard good and bad things about them i am mechanic in the USAR so Ive got basic skills with working on things is there common problems i should look out for or any advice will be greatly appreciated.



Thank You
SPC Brown Alexander J

[pocket-rocket]

First off, welcome to the site and thank you for your service

Common problems to look out for:

Timing belt neglect. The change interval is 60k miles and it rarely gets changed then. Inspection covers are easily removed after the two 8mm bolts are taken out.

Lower intake gaskets. The gaskets between the LIM (Lower Intake Manifold) and the head is a really really stupid design. It's about 1/8" or so of plastic with about 1/8"-3/16" or so thick sealing material on each side... There is a good sized gap between the LIM and the heads and GM filled it with gasket. If one day when the car is warming up it idles high and will not return down to a normal idle until it warms up, it's your intake gaskets leaking and letting in air that the throttle body and idle air control valve are not controlling.

Distributor plug. Yes, I said distributor and your car has an electronic distributorless ignition system. Your car also has 5 cams, not 4. One is in the center of the block like a pushrod, but it has no lobes. This 5th cam turns the timing belt on the accessory side and the oil pump on the other end by way of the distributor plug. Think distributor cut off about 1/2" outside of the block. They have an o ring on them to seal them, but over time the o ring gets brittle and begins to leak. The proper way to do it is to remove the plug and replace the o ring, but removing the plug requires the rear head to be removed. Some have ground down the LIM bolt ear that the distributor plug hits some and raised the plug high enough to seal under the head of it. One guy that I recall used teflon tape rolled up into a string shape. I've used distributor gaskets from a Chevy 350 and silicone with success.

[tunerz34]

thanks for the info is there anything eles i should know diginoseing tips or anything speacial cause my dad said the car is running ruff when its warm and is not sure why he thinks it might be the timing considering the guy i just bought the car from had the timing belt brake on him while he was driving and he replaced it hims self and then parked the car and said it wasnt running right since then could be anything eles since it was park for a while

[pocket-rocket]

I would lean more towards he didn't time it correctly if he isn't familiar with the LQ1 and lined up the cams by the paint on the pulleys. If the timing belt has been done on the car correctly any time in its life, the paint marks on the pulleys doesn't mean squat. Rough running after warmed up could also be an O2 sensor since the ECM won't use it until it's warm.

If you don't know any maintenance history on it I would start with a can of Top Engine Cleaner from a GM dealership (http://60degreev6.com/content.php/65...Engine-Cleaner), then give it a good tune up and O2 sensor. If it isn't cleared up after that, I would attack the timing.

[tunerz34]

awsome thanks for the advice i give you guys credit the is one hell of a compicated motor nothing like the idiot proof army trucks that are made to come apart

[pocket-rocket]

You should see some of the newer DOHC engines, like the 3.6 and 3.6 with direct injection that puts out something like 305hp in the new Camaro.

[tunerz34]

yea ive read about them since ive been over here i would love to drop something like that in my gtp but it would probably be a nightmare to do and expensive