My son is in the middle of his second attempt to replace the HG of his 91 4 Runner. The first try ended up with compressions of: 90-170-165-90-110-85.
When he was ready to install the second gasket set,(FelPro-MLS), he noticed that the gasket will block many of the coolant passages between the block andv heads. Other than that, the gasket lines up perfectly.

Any ideas?

 

Be sure you haven't got them up side down, and you do have left and right.

 

Throw the FelPro in the Garbage

Get some OEM Toyota head gaskets.

 

DO NOT install them that way. You'll be taking it all apart again. The gaskets are probably upside down.

 

http://engnbldr.com/ All very good quality parts. Seems like everyone on this board recommends them. You can also use their ebay store. Get rid of that felpro crap. Their is a big debate about it, but make sure you have new head bolts.

 

make sure that there is a left and right side!!!!!!!! also like to add was the reason the heads pulled because of compression leaking between the HG's? did he have the valves and seats ground how about shimmed?

 

FEL-PRO is TOYOTA OEM head gasket I believe... correct me if I am wrong.

The HG should have a left and right mark on each of the gasket, Left bank should be on the driver side and RIGHT bank should be on the passenger side, and just like you said it will block some coolant passages, it does this to maintain the flow of the coolant I believe, on the front of the engine right bank should be cover by the HG and if I remember it right the left front bank is open, and face the copper toward the engine block. Also hold the HG in place when you are about to install the head, it will slip alittle down and the cylinder wall will be in touch with the HG copper, I balance mine when I did mine.

 

personally im using enginebuilder's Rock Gasket! Looks to my untrained eyes to be better than the origional!

 

Fel Pro is Fel Pro, If by Toyota OEM you mean that Fel Pro supposedly designed them to Toyota's specs then yes, but they certainly aren't as good as Toyota's

 

What are you talking about? The gaskets should NOT block any passages. If they do, the engine will have problems.

 

The gasket will block some and will let some un-block, when you lay the gasket on top of the block it will cover a few passages on most of the cylinder surrounding.

 

this is true

 

That's just crazy, so why did the Toyota engineers put passages there if the gasket was just going to block them? IMHO the gasket is wrong or upside down.

 

its like that on all engines. The gasket determines where the coolant flows and how much flows....

 

So you mean like the design team engineered the water jacket, tested it with a prototype and found it was cooling too good, so rather than redesign and fix it right they stuck a bandaid over some of the passages?

 

Sounds about right to me :pat:

 

Thanks Everyone!

I think that explains it. They may have redesigned the gasket to reduce failure by having fewer openings. He definately has the right/left correct and they are not upside down.

Another thing I just read on HG failure in general- the head has been resurfaced so you have to make sure the new bolts are not bottoming out.

 

I truly do not know, I did not do my HG. Did not have the time or the experience. It does not make sense in mind though to block the passages. Good luck

 

Toyota OEM is make by either Nippon-Denso, Aisan or Kyosan-Denki.

Fel-Pro is Fel-Pro.

New OEM Head Gaskets are $36 for a set.

 

No not what I mean. Look at any of honda's I4's D16, B16, K20, etc and youll see ENOURMOUS voids btwn the cylinder walls and the block walls for water to flow.

Here is a pic of a Mitsubishi I4:



Now here is the HG for that engine:



Now here is a pic of a B18 Honduu block:



And the same block with it's OEM HG:





This tells me that the HG is used to control how much water gets where given X amount of pressure....remember that in fluids under pressure will take the path of least resistance. This is why the water passeges of the HG are so small near the water pump. It's a much higher pressure there then at the other end of the block. So to get equal flow the sizes change.