Anyone done a head gasket 1gr-fe?

New...and looking for tech advice
Hi I'm new to the forum...long time 2nd gen Tacoma Owner. Bought her new in 05 double cab 4x4 4.0 v6. She was originally black, but the Southern Az sun ate the paint right off the roof and hood...she's been repainted white with flat black accents on the fenders etc for about 4 years now.

With almost 190k trouble free miles, I'm starting to lose a head gasket. All the tell tale signs, brown pasty goo on the radiator cap, bubbles coming up through coolant from compression stroke bypassing the head gasket into the cooling system, and it did have an obvious miss on cold starts and a P0304 code, but those have gone away and it's currently running just fine. No signs of coolant in the oil...

Does anyone have experience with replacing head gaskets on this set up? Most research I've done, almost everyone has said the engine must come out. A few have said it can be done without pulling the motor. Just wondering if anyone has first hand knowledge of doing this job with the motor still in the truck? Any advice at all would be greatly appreciated. Thanks!

 

I have not done one on this particular engine, but I have done several on engines that are more crowded. For example, a Ford Mustang Cobra DOHC. And we did it without pulling the engine. The last one we did was to replace 3 broken valve guides caused by my son missing 3rd gear at the drag strip. It was a pain, since the 4.6 is similar to the 4.0 1gr engine, you have to clean off the front of the engine so that you can remove the timing chain cover. You just have to be patient and careful, and keep up with parts. Take pictures if you don't feel comfortable with remembering where something goes, and when you disconnect things, nothing like a piece of tape with a number on both sides so there can be no confusion about which line goes where...

I'd suggest the service manual so you know what MUST be replaced (IE torque-to-yield head bolts and such that can not safely be reused). It will also be critical to re-timing the engine when you reassemble and get to the point of installing the timing chains.

That said it is a much easier job with the engine out. It can get painful to lean over into the engine bay for hours on end. But it can be done.

 

Thanks Robert. I've done the job on other motors as well, but I was told by a dealer service writer that the oil pan to timing chain cover simply can not be done correctly with the engine still in the truck. I'm leaning toward pulling the motor...just to make absolutely sure I can get to everything correctly, take my time and fix and clean up everything else I may find. I'm still just hoping to hear from someone who might have first hand experience with this and get their input.

 

People in this forum have done head gasket jobs themselves without pulling the motor. Unfortunately those who did it themselves did not take pics to write up a tutorial.

 

Knowing my truck ('07 prerunner 1gr) the front end of the motor is not crowded. Nothing like that damned 4.6 DOHC. Only thing I don't like is the prerunner sits pretty high. I have done a couple of timing belt replacements on a family member's 03 tundra, and it is not that comfortable a job. Have to take off his brush guard to be able to get to the front end. And I used a couple of ramps to stand on when I needed to reach any distance that was not easy from the ground. That v8 is a bit longer, yet we had no problem whatsoever removing all the crap to get to the timing belt covers.

If you do this, do look carefully. I saw one photo here of someone with a head gasket failure and combustion gasses actually eroded a small valley into the top of the block where it was leaking out of the cylinder opening. Not something you might normally be looking for. Probably a good straight-edge and light to see if you can see the light under the straight-edge will be the safest test.