Oem head gasket or aftermarket which is better?

But the OEM head gasket is what gave you trouble in the first place.

When that fateful day comes to my Gen3, it's getting an American Made Fel-Pro replacement head gasket.

 

That's always kinda been my opinion on the matter. There's no way in hell I would use the actual original HG. Supposedly it's been updated, but it sounds like they just covered the whole thing with the black material that goes bad on the original so I still would want something that appears to work well with no 'coating' whatsoever. Also, I've never dealt with a dealership that knows anything about anything so I'd probably get old stock or something.

 

I’m wondering, if you installed say a Felpro gasket, eight o’clock day one, then ran it for 200k miles, without touching the EGR, would it fair any better?

maybe it would, but on the other hand, it might be a shooting-the-messenger case?

 

Trying to find just one thing is the problem with the egr and head gasket material theories. Yes they contribute. No because it is more a function of excessive carbon from rings and cylinder cooling design not fixed till gen4. Uneven cylinder cooling also impacted by thermal cycling. Thermal cyling is the straw that broke the camel's back. All resulting in small self sealing warpages. Don't forget the same engine in a Corolla has not been nearly as bad.

Look up Root cause analysis.

 

That would be a good test!
Because it's just a theory that keeping the EGR system clean will make the head gasket last like it does in other engines.

My theory is: Disconnect the EGR so there is never a chance of having uneven flow of EGR gasses at the individual cylinders.
Haven't gone out to the car and done that yet.

What's the worst that can happen? I now have a Corolla engine under the hood? I now get X less MPG?

Both questions take time to show any results,,, so,,,,,

Maybe it's the 'Thermal Cycling' theory and neither will change the life of the head gasket.

 

Well my OEM gasket failed at 350,000 miles so I don't really see that as a quality issue.

Posted via the PriusChat mobile app.

 

Incredible! You must be the record holder!!
Are you the original owner and know the complete maintenance history of your car?
Is so, could you share?

 

I mean, look around. It's a major failure point and they almost all fail the same way, it's clearly not that high quality. A few examples don't dis-prove that.

You just can't over-heat a prius, like ever. So if your water pump fails and you don't immediately stop driving, your head gasket is done. My old Saturn over-heated like 10 times and never had head gasket issues. I think it actually is purely just a quality thing. Keep it cool and you'll be OK. Still seems crazy to me to put in a non-updated OEM head gasket.

 

The fact that something fails is not necessarily an indication of its quality. Put through enough loading cycles, any solid material will eventually fail due to fatigue, and a head gasket is no exception. Whether or not the failure is premature could, however, be taken as an indication of quality.

In a Prius the ICE starts and shuts down multiple times during a single drive cycle, whereas in a Saturn (or other non-hybrid) it remains operational throughout. In both vehicles the HG expands when the ICE turns on, and contracts when it turns off, so one can easily imagine the Prius HG going through at least an order of magnitude more expansion/contraction cycles than one on a Saturn.

Once a sufficiently large number of Saturns have completed more than 1,600,000 miles on their original HGs, it might be fair to come back and knock the OEM Prius HGs that fail after 160,000.

 

.


I’m just sayin’ ...


[<<. Who makes OEM Toyota gaskets?

ISHINO STONE® – Corteco Ishino Corporation of Japan – has been manufacturing gaskets since 1932 and tier-1 OEM supplier to Toyota, Honda and other Japanese auto manufacturers. >>]

 

Fair enough, but then wouldn't other hybrids also have major issues with failing head gaskets? Do they? I'd be willing to bet that 3rd Gen Prius with a higher quality gasket would last much longer... But sure it's all conjecture.

Isn't it the coating that wears away? Isn't the metal OK, and aren't aftermarket head gaskets often all metal (no coating)?

 

I believe it is thermal cycling of the block and head that allows slightly acidic coolant to slowly attack the black sealant impressed on the metal head gasket

A later revision of the gen3 Toyota hg expanded the black sealant layer. However gen4 redesigned the entire coolant passage geometry and added a cylinder insulator to improve temperature consistency of the cylinder itself.

Gen4 Insulator and Coolant Passages

 

Just remember, the head gaskets for the 4th Generation engines are failing also....

 

Overheat your engine and it will blow a head gasket. People often drive with their temperature icon on. Gen3 does not require an overheat event.

 

By this reasoning any engine that is used in a Hybrid platform is going to have HG failures more often then the same engine in a Gasser.

 

Thanks for posting this pic of the thing that is placed in the block of a Gen4.
Other than that are the block and head the same?
Maybe 'another' improved head gasket design?
You call it a 'cylinder insulator'. I don't see how that description works.
Maybe it's a 'flow mixer', or such, to 'stir' all the flowing coolant to make contact with the block more even.

There could be eddys or backwater areas where the block runs hotter than average...
Such as between #1 and 2 where the failures commonly occur?
Which is also where the EGR passages get the most clogged, creating uneven flow of EGR gasses to the cylinders.

Hence: the two leading theories of why the dang head gaskets fail routinely...

Either way, did the thing help with head gasket life in the Gen4's?

How exactly does one 'Overheat your engine'?
I assume the water pump has to start failing... And the dumb driver presses on regardless....

Do you recommend replacing the water pump proactively at 'X' miles?

 

No the engine in gen4 is totally redesigned. All parts, even the water pump, cylinders, head, egr, aux cooling lines.

Gen4 has no inherent engine problems. A leaking exhaust coolant recirc system has taken out gen4s due to overheating drivers ignored for 5 minutes.

Overheating means something fails and the driver assumes he can make it three more miles and or does not realize what the lights mean or thinks the temp light that flashed and went away is nothing.

Gen3 really has no chronic overheating problems and egrs do not cause failed head gaskets. Toyota has updated pistons, rings, intake, egr valve, head gasket and ecu software to improve gen3 engine reliability. To get it in your car means a pro rebuilt engine with all of those things or a 2017-2022 gen3 JDM engine.

 

The cylinder "insulator" is foam to even out cylinder wall temps in gen4s.

Sometimes our paradigms have to be shifted.

 

Some here would definitely question this statement.
I don't know.
I'm on my 3rd Gen3 and still trying to figure out the best route to avoiding the dreaded HG failure....
I sold one while it was in the beginning stages of the failure... shame on me...

So, RJ, what about replacing your Gen3 water pump before it fails? Do you have an opinion on that?

I'm currently at +10k mi with the EGR valve disconnected.
I can't detect a change of mpg. And, I know the engine is NOT getting uneven EGR flow.