Truck is running rough on startup

Well I checked it cold on a slope, let it sit for a few hours and checked it cold on level ground. The coolant level is totally fine. Not low at all. Only the resevoir looks a little low. Under the cap it’s not low. I looked at the oil cap and it’s not milky at all either.

 

I hope it is something simple. I had the same exact thing happen in March. Bad HG at #6 for me. It is not cheap. Had to send the DS head to the machine shop. It's a complete upper engine teardown for this.

 

How did you know it was a gasket? Did you test it?

 

Ok, so Toyota headgaskets don't ever show up on the chemical test *the blue fluid

So there's a few ways to catch it.

My way. This is a 4.0 with cold start misfire.

https://youtube.com/shorts/_oWXDmrs96c?feature=share

After bleeding the system, the bubbles should stop, small stream of tiny bubbles almost always means combustion.

Other way is to get it RED hot, then quickly remove the spark plugs. Watch inside each cylinder for coolant or a "fog" of coolant entering the cylinders.

 

I'm doing both head gaskets and all new timing components soon. Doing the work myself except for the head refurbishing...

The collection of gaskets o-rings and other misc. parts. Almost have everything that's needed..


Found these gems at Rockauto, saved a ton of cash..

 

I followed some clues to determine for sure that I have a leaky HG. Those clues were, a misfire at first startup and going away shortly after engine is running. Low coolant level in the radiator. Swapping ignition coils from the suspected cylinder with a good ignition coil, misfire condition remaind in the suspected cylinder.

 

A small amount of coolant loss and the diagnostic trouble codes. I took it to my local dealer and had them look at it and they came up with the same diagnosis.
It can also ruin your catalytic converter if you go to long.

 

So far it does not seem like I'm losing any coolant at all. Also my p0138 code is very intermittent. p0138 is high voltage at the circuit and the 02 sensor wiring does look corroded. What codes were you seeing?

 

Just curious if anyone might think this could be a leaking fuel injector? The intermittent code is a P0138. One of the causes of the P0138 is a leaking fuel injector which can also cause a rough idle while cold at startup.

 

Guys, he's got an '09 - not exactly known for HG issues. There's dozens of other things to check for first.

 

What would you be checking first? I wiggled some hoses around and couldn’t find a vaccum leak. The most noticeable symptom is that on a cold startup it runs rough enough to create a rattle but the rattle only occurs in drive with my foot on the brake and on an incline or decline.

 

I’ve had a suspicion of a possible leaky injector for awhile. I’m going to look at some videos of how to check that.