I started my vehicle after replacing the head gaskets. It lept to life right away, with no SES light or fault codes. After idling for 5 mins, a light exhaust smoke started to come from out the engine either where the exhaust manifold connects to the head or from the space in between the head and the block. i also had white smoke coming out of the tailpipe (prior to this job, neither happened). No over-heating occurred.

I am assuming the heads and/or the exhaust manifold are not torqued down enough or evenly. Can I remove the valve covers and rockers and retorque the head bolts and exhaust manifold bolts or do I have to replace the head gaskets and bolts again? Should I have it pressure tested?

is it ok to start it again and record some video of the engine?

 

Don't rush into anything yet. It may just be assembly oils burning off on the exhaust manifolds and such. Not uncommon to have white smoke out of the exhaust, also. You may have coolant residue leftover in the exhaust system and it has to burn off.

Start it up a few more times, just keep an eye on your guages and let it go through a couple heat cycles.

What type of exhaust manifold to head - gaskets did you use? Most kits I've seen, come with those thin steel ones...I bought the thicker ones...and had no issues.

Now, if you do actually have an exhaust leak...between the head and block...you're looking at doing the whole job over again.

Brian.

 

Drive it around for the mean time. No overheating etc it should be fine. Smoke could be coming from drips during the process of removing components earlier. Let it completely dry for a while. Did you get a complete gasket kit?

 

If it was a HG Leak it would sound like a Spitfire or old Harley Davidson. It could just be the exhaust manifold gaskets & burnoff.

 

The visible smoke near the exhaust manifolds and bad exhaust smell stopped. There is no Harley/spitfire sound and no white smoke coming out of the tailpipe. The Disco is running better than ever, with a quiet steady idle, good pickup, no misfiring, coolant temps no higher than 98 deg C. However, the expansion tank is pressurizing after running the engine a few mins.

Today, after a three-mile drive, the SES light came on. Fault code P0134 — oxygen sensor failure. In late 2014, the vehicle failed the CA smog test for the same reason: P0134/no activity bank 1 #1 sensor. That sensor was replaced (but not the bank 1, #2 sensor), and it passed. Is the failure of the same sensor 3 years later a coincidence or is it related to an exhaust leak?

 

First, the cooling system is designed to operate under pressure. No pressurization of the reservoir after the system is up to operating temperature would indicate a leak somewhere.

Yes, unfortunately the average lifespan of O2 sensors in a DII is short, relative to any other vehicle I know about. And worse yet, sometimes new sensors are bad right out of the box.

 

I cleared the code and took the truck for the same drive today . . . and no SES light came on when I requested codes, none were available. If the sensor has failed, surely the ECM would notice. Truck still running very well despite ghosts in the machine.

 

Great. thats nice. Hoping you get pass 80 plus miles to be sure codes are gone. Cheers!

 

This^^^

The system is pressurized to maintain higher operating temperatures. It is normal to feel some pressure, while removing cap after running...that's why there is a warning sticker telling you not to open the system...while at operating temperatures or after running for a while.

As far s the codes go...drive it for a bit and recheck in a week or so. Don't rush to judgement on these types of codes right after a head gasket/rebuild job. Let things get back to normal, such as, getting all residue of anti-freeze out of exhaust system and such.

Brian.

 

Did you change your oil after you buttoned everything back up?