968to986

On the Lindsey Racing website, when you go to order a head gasket, they ask if you want their $10 coolant mod. I tried searching but couldn't find any info about it. Does anyone know what it entails and what it does? Thanks!

Perry 951

It is a steam vent for the #4 water jacket. There is a tented portion of the head above #4 that easily develops air pockets. The mod is to drill and tap the head at this spot and run a plastic water line back to the reservoir. It works great.

MAGK944

V2Rocket

not sure if LR is offering this as their service but on the 928GTS, Porsche added a few small holes on the exhaust side of the heads (and in the gaskets to accomodate) to allow for coolant to flow between the ports/valves.
can't hurt.

968to986

Yeah, I understand the Steam Vent Kit (which I do plan to do BTW), but I believe this is different. Seems like just a mod to the head gasket.
Wait, what? People use the phone to call each other? Yeah, calling was next on my list, I just wanted to see if people had first hand experience.
I'm imagining that there's a coolant port or two that the normal head gasket doesn't have holes for. Guess I'll find out when I call.

bw993

Spencer is correct. LR adds holes to the gasket for coolant to flow thru.

Perry 951

Apparently I've been out of the game for WAAY too long. The steam vent kit is so 2005, now we're drilling holes in head gaskets? I'd like to know the info as well.

bw993

LR adding coolant holes to the head gasket has been around for awhile, but not really utilized by most owners. I had one gasket with the modification done years ago. Can't attest to the benefits since I also installed the vent kit at the same time.

zmf

Hmmm. I'm about to order parts from LR, including a Cometic gasket. If I'm understanding the conversation, without this mod, at least some coolant ports are blocked? That doesn't seem like a good thing.

rlm328

Porsche at this stage of the game were not real proficient in water as a coolant. The cars they were producing were "air" cooled (really oil cooled) The designs in the water cooled engines leave a dead spot back by the #4 cylinder where a steam pocket can form preventing cooling of the #4 cylinder leading to head gasket failures among other things. I do not know how a couple of holes would alleviate this condition. The steam vent does work, one of its other benefits is having to burp the coolant system.

If you do not get your block and head machined I would think twice about the Cometic gasket. It requires a surface smoothness of 50 RA or less.

zmf

Thanks. At least that much has been done.

V2Rocket

look at a 944 head, then the gasket.
lots of holes are 'blocked' by the gasket, only flowing up through the gasket behind #4 cylinder.

i cannot say with certainty what LR does as their coolant mod, which is different than the steam vent kit, but i speculate it is opening up some of those blocked holes.

blade7

Casting the block and head waterways, and then blocking some off with the head gasket doesn't sound like a random exercise. I believe the 104mm blocks have a different water flow. Perhaps Porsche knew what they were doing.

Thom

Either some of the holes in the head are there due to the casting process and are not supposed to let coolant flow through or the headgasket is supposed to be exposed to coolant on both of its sides to avoid heat to build locally on "large" areas of the head surface. Or perhaps a bit of both.

The headgasket is not "holed" on the corresponding locations to avoid interfering with the flow of coolant, which flows backwards in the block from the water pump then frontwards after it went up in the head through the 4 triangular holes at the back of the head(gasket). There are still two small holes at the front of the headgasket which are so small that they should not alter coolant flow.

zmf

IF you get around to calling LR, please post their response. But I know what you mean about verbal communication.

What I'm hearing seems to suggest that the head gaskets sold by LR are indeed specific to 951's, as opposed to generic gaskets that require modification for use in 951's. That they are copies of OEM gaskets. But they might (or might not) be improved if more ports were exposed.

When do we get to the easy, straightforward stuff??