How to diagnose head gasket - LQ1

[06goat75]

Got my car all back together and drove it up and down the driveway, with the end result being lots of white smoke out of the exhaust, and some under hood too.

Well, I didn't get a chance to drive it much before I tore into replacing the LIM and fixing the oil leak, but I sure doing remember that much white smoke.

Removed the upper intake again and re-torqued the LIM bolts, I believe I read somewhere on here they were supposed to be 18 ft/lbs, but the service manual (which I didn't have at the time) says 22, so re-torqued them to the right number, replaced the heater hose output from the lower intake manifold since that "quick disconnect" fitting broke (and was leaking).  Checked everything, and get a lot less white smoke, but still have some.  Also have some white smoke (which smells like coolant) coming from the engine compartment, drivers size, rear head area.  Spent a lot of time looking yesterday for something dripping, trying to find the leak, but no success. 

Anyways, phase one is to re-do the LIM, maybe I screwed up the gasket since I didn't torque it right the first time.  One of the bolts didn't want to torque properly, so I need to install a heli-coil too.  

Hopefully, redoing the LIM fixes it, but I might be going for the head gasket.  It is a LQ1, so I'm not going to just do a head gasket unless I have to!  

What's the best way to diagnose a bad head gasket?  I don't see coolant in the oil (haven't drained it though), but I get bubbles in the coolant overflow bottle, after I shut her down.  White smoke out the exhaust.  White smoke coming from he exhaust crossover area, under the rear head.  After I get everything back together, I'll try to track down a coolant system pressure checker and see where that gets me.

 

  

[walterdude]

I just went thru pretty much the same things with my Blazer... It was going through ALOT of coolant... AND couldn't find a leak ANYWHERE!!! It wasn't smoking thru the exhaust but could smell a strong coolant smell...  No milkshake... Finally it started REALLY leaking,,, As fast as I filled the coolant it leaked/poured out but still couldn't find the source of the leak... Finally got a few friends to help... One under the car 2 up top and me to check things out... To be fair with myself I'm waiting to get Cataract surgery done on my eyes,,, SO... I am pretty much blind!!! Finally found it... It WAS the intake mani gasket... Found just a bit of bubbling at the front of the engine/LIM... It was following the engine to the rear and down and coming out from the bell housing area... Replaced LIM gasket and all is good now (seems to be)... (fingers crossed!!!) Things didn't go all that easily,,, DID get it done tho!!!

 

Don't know if this will help at all,,, being completely different engines... From my LQ1 days I seem to recall the first gens didn't have a water jacket in the intake,,, only in the TB and the coolant couldn't get in the oil... It's been MANY years since I've had or worked on ANY 60 deg engine!!! If I got anything wrong,,, SORRY!!! Just got me thinking about my recent ordeal,,, so,,, I posted!!!

Good Luck!!!

Tom B...

Sometimes you can hold a piece of paper up to the exhaust outlet and if the paper stays there or sucks a hole in the paper it's probably HG...

[walterdude]

There are Kits available that you send them a sample of your coolant or oil and it will tell you exactly what is in there

Tom B...

[06goat75]

On 2/9/2020 at 1:30 PM, walterdude said:

Finally found it... It WAS the intake mani gasket... Found just a bit of bubbling at the front of the engine/LIM... It was following the engine to the rear and down and coming out from the bell housing area... Replaced LIM gasket and all is good now (seems to be)... (fingers crossed!!!) Things didn't go all that easily,,, DID get it done tho!!!

Good Luck!!!

Tom B...

Sometimes you can hold a piece of paper up to the exhaust outlet and if the paper stays there or sucks a hole in the paper it's probably HG...

 

Thanks.  Spent the weekend tinkering with it.  Replaced the LIM gasket (again) with a new set of Fel-pros.  Torqued to factory specs (even using the hold down bolts, as required by the service manual).  

Did the dye thing in the coolant system.

Found a leaking hose (upper radiator) so replaced that too.  Still get white smoke out of the exhaust.  It is in the 40's out, so I have been having the discussion with myself if it is smoke, or just standard condensation from a car warming up.  But, I drove it up and down the driveway, and it stays pretty white.

Coolant system pressure check to 15psi.  I haven't been able to find the test specs, but it goes from 15psi to 5psi in about an hour, so it seems to be losing pressure (though not quick).

Still get some smoke from under the hood after it warms up, haven't been able to track that one down yet.

At this point, I'm not sure what else it can be besides a head gasket.  Any one have any other ideas as to what to check?  

Don't mind the work, but hate the thought if tearing that deep into it if it could be something else I'm not thinking of.

 

[rich_e777]

If you use a coolant pressure tester and it doesnt hold pressure then maybe you could use a plastic straw to check for coolant in one of cylinders? Stick the straw in, put your finger over the end and pull it back out.

[Schurkey]

Assure that the radiator and the overflow bottle are "full", and that the coolant system is properly bled.  Put two gallons of coolant on the passenger seat.

DRIVE THE BITCH so that all the coolant in the exhaust system boils out.  Not less than 20 miles unless the coolant level is dropping.  Might want to stop at 5 and 10 miles to assure that the coolant level hasn't dropped.  Top off as needed.  If the coolant level drops, it's leaking.  Compression test and cylinder leakdown test to find which cylinders.  (First Guess:  #1 or #6.)

IF you still have white smoke after 20 miles. you're looking for a coolant leak into the cylinder/exhaust.  Compression test, leakdown test.

 

No smoke, watch the coolant level until you're sure things are good.

 

'Course, you could just do the compression test and leakdown test BEFORE you drive it,  This could confirm that there's a leak.  But you aren't going to know for sure until the exhaust gets thoroughly heated-up.

Edited February 11, 2020 by Schurkey

[55trucker]

There is another way to look for a cylinder that is leaking into the coolant system, one will have to sacrifice a cylinder compression tester, one removes the braided hose end from the gauge, then installs a male barb quick release air fitting into the open end & secures it, now assuming that you have an air compressor one screws the spark plug end into each cylinder & pumps in 100lbs pressure. Remove the rad cap, if there is a leaking head gasket to the coolant system this will find it. This is also a good way to find leaking  valves that are not seating, with the piston at TDC compression all valves should be securely closed, if there is a valve that is not you'll here the air (whoosh) at either the tailpipe or the throttle body.    

[06goat75]

Thanks everyone, appreciate the discussion!

 

Finally got it out on the road and drove it about 10 miles (it just started snowing, so didn't want to get too crazy!).  

While I haven't ruled out a head gasket, might be off the hook.  

Block test (color change fluid to check exhaust gas out the radiator) - Negative

No bubbles in the coolant

No milky oil

White smoke out the exhaust has diminished quite a bit (changed the modulator on the transmission)

Doesn't seem to be using coolant - though I'll drive it a few more miles when the roads clear up (hopefully tomorrow).

Pressure checked the coolant system.  Held 15 PSI for a bit, and dropped down to 5 PSI over the course of an hour.  While I can't find the specs in the manual, I believe this isn't out of the ordinary.

 

Still want to do a leak down test though.

 

Now I have a new symptom though - gas consumption!  Seemed to use almost 1/4 of a tank in those 10ish miles!

Edited February 12, 2020 by 06goat75

[55trucker]

Loosing pressure in the cooling system is normal after shutdown, as the engine temp dissipates the pressure also does the same as the coolant contracts.

Not knowing what you're using to bleed the LQ1 it IS a specific method to doing so, in my opinion one should make use of a coolant bleed funnel to properly do so, it's not unique to just this engine but any engine where the rad filler cap is placed lower than the most high point in the cooling system. Using one of these makes the job considerably easier.

 

 

Edited February 12, 2020 by 55trucker

[06goat75]

2 hours ago, 55trucker said:

Loosing pressure in the cooling system is normal after shutdown, as the engine temp dissipates the pressure also does the same as the coolant contracts.

Not knowing what you're using to bleed the LQ1 it IS a specific method to doing so, in my opinion one should make use of a coolant bleed funnel to properly do so, it's not unique to just this engine but any engine where the rad filler cap is placed lower than the most high point in the cooling system. Using one of these makes the job considerably easier.

 

 

 

Thanks for the intel.  Usually bleed it with the front end on ramps, bleeder screws open until coolant seeps out.  Funnel looks easier though, I'll look into it.

[55trucker]

 

49 minutes ago, 06goat75 said:

 

 bleeder screws open until coolant seeps out

That approach is a typical mistake,

with the engine running one leaves the bleeders closed until the system is warm to hot, having the funnel in place before you start one fills the funnel to 1/4 full when the system is cold, as the system heats up the fluid will expand and rise in the funnel, air pockets will be forced out thru the funnel, the fluid level will drop accordingly, with a now warm engine insert the stopper into the funnel & let the system pressurize.

Now crack open the bleeders just enough to get airflow/fluid, close again when no air appears, repeat the process multiple times until no longer do you see air at the bleeders, with the engine still running remove the stopper, if the air has been removed the fluid level in the funnel will drop slightly. Return the stopper, shut off the engine and let it cool, as the temp diminishes the coolant contracts, when cooler pull the stopper again, notice the fluid level,  it should drop to a stable level, return the stopper & now remove the funnel from the filler neck adapter, empty the remains into the reservoir, pull the adapter from the rad neck & the fluid level should be right there. You're done, the entire process take a good 75 mins.       

Edited February 13, 2020 by 55trucker