External Head Gasket Coolant Leak

Looking for some thoughts & advice from the TW crew.

While working on the wiring harness for a P0333 knock sensor code last week my dealer found dried coolant on the intake manifold of my 2015 4.0 DCSB. The truck has 150,000 kms / 95,000 miles.


Other than a P0022 code which popped up and cleared itself a few weeks ago the truck has not exhibited any issues while driving. We did a compression test and everything looked good.

The dealer suggested that the leak is likely coming from the head gasket but it is only leaking out into the manifolds, no coolant is reaching the cylinders.

We did a little more diagnostic work chasing the P0022 code and it looks like the timing chain is stretched and also needs to be replaced.

All in the head gasket and timing chain are a 30 hour / $8500 Canadian repair at the dealership. 24 hours HG / 15 hours timing chain or 30 hours when done together.

The dealer thinks there is a good chance the HG coolant leak could go for years or indefinitely without creating a serious issue. The fact that the coolant is dried vs wet suggests to them that this is a small leak. To back this up they offered to discount the labor from the timing chain replacement (15 hours) from the HG replacement (24 hours down to 9 hours) if I do need to do the HG in the future.

My options are;
- Shop the repair around for a better deal at a private shop
- Trade in the truck for a new Taco (delivery would be Feb approx) or find a lightly used newer taco
- Do the timing chain at the dealer now and hope for the best with the head gasket

I do love the truck and would like to keep it but none of these are great options.

Does anyone have experience with coolant leaking from the head gasket without effecting combustion? Did the HG eventually go or were you able to keep driving it?

Interested in everyone's thoughts.

Thanks

 

Did they pressure test the cooling system?
Usually stuff leaks when cold, and can sometime seal when hot.

Anyways, I’d pressure test the cooling system and take a good look.

FWIW, I know guys that’ have spilled coolant in places it didn’t belong.
Accidents happen, coolant runs to places it shouldn’t. You never know?
After all it’s dry? Right?

 

As far as I know they did not.

That's a good call, I'll ask them to do this tomorrow am.

 

That's interesting I've never seen one leak there although I did see a post awhile back of one that had a headgasket leaking externally on the exhaust manifold side, really low milleage for that kind of problem too.
I would want to be 100% sure it's not coming from one of the coolant pipes or o-rings before condemning the headgasket.

 

Exactly, like that big pipe right there in the middle.
I believe it uses an O-ring, I can’t remember?

 

It does, found the post OP
https://www.tacomaworld.com/threads...lant-outlet-pipe-tacoma.696557/#post-24642807

 

Yes it uses O-rings on both ends and the aluminum piece it goes into I believe uses a gasket on both sides where it bolts up to the cylinder heads.

 

Yeah, the link above a lot of good pic.
I honestly forgot about that post, and I even replied to it.

 

Thanks for this!

I did read through this post and brought up the possibility of this 'coolant outlet pipe' causing the leak. I don't think I did a great job of explaining this to the shop manager. I'll review this post and bring it up to them again tomorrow.