Castech heads question/opinions welcome

[Kraig]

I recently acquired a 2003 Suburban with 229k miles from auction. It was low on coolant when I bought it, and is consuming coolant with no visible puddles or clouds of steam from the tailpipe. It has 706 heads and through the oil fill hole, all surfaces appear dark brown with the exception of the head bolt, which appears clean-looking and golden colored. Hopefully the pic will work—it’s out of focus but I think conveys what needs to be seen. What say ye—time for a head job?

 

[iamdub]

I recently acquired a 2003 Suburban with 229k miles from auction. It was low on coolant when I bought it, and is consuming coolant with no visible puddles or clouds of steam from the tailpipe. It has 706 heads and through the oil fill hole, all surfaces appear dark brown with the exception of the head bolt, which appears clean-looking and golden colored. Hopefully the pic will work—it’s out of focus but I think conveys what needs to be seen. What say ye—time for a head job?

View attachment 230008

My experience with the Castech failure is that the coolant was leaking so slowly and burning off quickly enough to not cause a milkshake in the oil. But the remaining chemicals/residues remained in the oil and, over time, sludged up the whole motor.

I don't see sludge buildup in your pic. It looks like normal oil staining for 200K+ miles. If you don't see any traces of an external coolant leak (white chalky trails) or smell coolant burning off, then it may very well be leaking and burning internally. If it were me, I'd closely inspect every external coolant route with a good light. Don't forget to check the bottom of the radiator and on the splash guards, all hose connections, remove the intake duct and check the coolant crossover connections under the throttle body inlet, the steam tube fittings, etc. If no evidence of leaks are found, send a sample of oil to Blackstone Labs for analysis then proceed from there.

 

[howie650]

I'd get an engine block tester and check for exhaust emissions in the coolant reservoir. The kit costs like $35. Can google Block Tester BT-500 Combustion Leak Test Kit.

Best of luck man.

 

[SnowDrifter]

I do feel it worth mentioning that the typical failure mode of a cracked head on these won't introduce combustion gasses into the coolant.

If you suspect coolant in the oil, find a place that does used oil testing and send a sample there. They can look for traces of coolant in the oil. Even if the coolant is 'burning off' it'll leave behind sodium and potassium as markers. Include which oil you use when you send it in, some have amounts in there as an anti foaming agent so they need to be able to reference something to see if any levels they find are elevated.

 

[retiredsparky]

A slightly hidden location of coolant leaks are the tee fittings at the fire wall above the rear of the motor where the rear heater hose connections are located. Rubber o-rings in these tees make it easy for the factory, but over time the o-rings can shrink and start leaking.

Also, auto parts stores sell an ultraviolet die and special led flashlight to help spot external coolant leaks.

Read up on adjusting valve lash on your lifters if you haven't done that yet.

Good luck with your build.

 

[SnowDrifter]

Read up on adjusting valve lash on your lifters if you haven't done that yet.

Puff puff pass

 

[Larryjb]

Check out post #31 here:
https://www.tahoeyukonforum.com/threads/latest-oil-change-oil-filters.99646/page-4

This test was done by removing the valve cover and pressurizing the cooling system. This was pretty convincing evidence.

I also confirmed the cracked head from an oil analysis. I really did the oil analysis to give me an idea of the condition of the rest of the engine. Other than evidence of coolant, all other metals were in acceptable ranges, so I went with a head replacement. Since the work was done, the oil has been a nice golden colour, even when the next oil change is due.