diagnosing conditions related to head gasket

I'm pretty sure I have a blown head gasket on my 97 Tacoma (5VZ-FE, 3.4L v6, 280k miles). I had low compression in cylinder 6 when I tested it about 1000 miles ago, and I had to keep driving because I moved across the country. After arriving, it started to have a persistent misfire and threw a check engine light. I'm considering replacing the HG, but I put the scanner on it to check the codes first.

I have a P0303 for a misfire in cylinder 3. Cleared the codes, started up again, this time I got P0300, P0302, and P0303, misfires in cylinders 2 and 3. The right side head gasket (bank with cylinder 3) was replaced 20k miles ago by PO. Can the blown head gasket on the left side be causing misfires in other cylinders, including on the other side of the engine? Timing belt was last replaced at 213k, 6 years ago.

Also, is there a reason for me to do a leak down test? I've done a compression test, and I used the color-changing combustion gas tester and found combustion gas escaping from the radiator. So it's pretty clearly a blown HG or cracked head, right?

 

Your driving a truck with a blown head gasket ? That can completely fail at anytime.

Coolant system pressure test.

The Last owner got the truck running with the least amount of work.Then dumped the truck.

Then sadly you bought the truck!!

A leak down test would be a great idea give you an idea about the valves.

Who knows just what be causing your misfires . Might not have anything to do with the head gasket.

Have you pulled the spark plugs?

at 280,000 any idea of the last timing belt change.

Best of luck!

 

Timing belt was last done at 213k, 6 years ago

 

I am not a snake oil salesman but every now an then there is a product that actually does what it is supposed to do, K-Seal is one of those. If it was me, I would throw the $30 ish at this and see what happens.


https://www.oreillyauto.com/detail/...head-gasket-repair/ksl0/st3501?q=K-seal&pos=1

 

I’ve heard about these sealers and I may use one to buy me some time. I’d like to do the head gasket replacement, though, and before I tear the engine apart I want to check whether there are other things I should be worried about.