Alan 91 C2

Maybe air cooled engines were pretty smart!!! LOL

GregBBRD

Anyone that has ever had the "blessing" of working on the VW buses with water cooled engines that did not have the coolant changed religiously (which was not common to have been done) would agree with you. What a disaster.

However, having worked exclusively on Porsches for over 50 years, I had to chuckle at this comment.
If you ignore all the problems that are unique to the 911 series vehicles, your thought is true, however that is really tough to do.
For instance, your 1991 model had chronic issues with oil/combustion chamber leakage due to the design issue of having no head gaskets.
And for the cost of fixing that issue, I'm pretty sure we could buy enough coolant for a 928 to change it every month, for our lifetimes.

The only models of 911's that were almost "design issue problem free" were the 1992 and later C2's with head gaskets.

Alan 91 C2

Thank you for the response.

Was a comment expected for no response. Well maybe the purist.

Greg, you have a respected position, earned by commitment to outcomes.

Every car engine has issues, driven by the accounts, we are mere mortals' in a complicated platform.

I appreciate your work, delivering superb outcomes from mere mortal solutions.

Almost, as discussed , as noted in 1992, is the "get out of jail free card for Porsche owners"

i have flogged my car at Road Atlanta, and turned on the AC, during the off ramp, These cars are designed to be run hard.

GregBBRD

Agreed.
It's always been amazing, to me (and to Porsche), why the 3.2 Carrera's worked so well without head gaskets, yet the 964's had issues.
Both are certainly the most durable of the 911 series.
I had a brand new red RS America, back in those days.
While not bullet proof, certainly a magnificent vehicle.

Kevin in Atlanta

Coolant in the block.

Head gaskets - bad shape

A few spots of corrosion that will require welding. You can see where the coolant became gelatin.

GregBBRD

Completely typical, these days.

FredR

Kevin,

If it is not too much trouble much appreciate if you can post some close up pics of the more severely damaged surfaces indicating the cylinder number impacted- I can usually fathom such out but like to be clear. I would also appreciate a pic or two of the gaskets- specifically the faces in contact with the head surface. Also if you have any info about the coolant type used historically in this engine.

I also noted with interest your use of the term "gelatin" presumably when referring to the apparent remnants max of whatever formed between the head and the gasket- perhaps you can comment as to why what you saw prompted this.

Did the gaskets show a complete breakthrough to the outer side in some spots? Kind of looks like it did. For sure the problem looked more severe on one of the heads compared to the other. I have yet to fathom out which head was which.

Have you managed to assess the depth of the corrosion experienced by any chance?

Kevin in Atlanta

I can do that - can you tell me who's coolant that is? I don't recognize the color.

FredR

As I am aware that is the colour of the VW specification G11 otherwise known as G48 by the BASF group Glysantin who in all probability derived it for the Volkswagen Audi Group. They also pioneered G-05 which to all intents and purposes is the exact same coolant chemistry of protection wise just that the G-05 has an additional component design to protect against a very specific type of corrosion associated with wet liners which of course is not needed in our engines [but does no harm]. The G-05 is a straw colour.

The Germans used this blue colour for purposes of continuity. Prior to this generic chemistry group they used a VW spec G10 which is the IAT type of coolant the US traditionally colours green. In Germany it was coloured blue so the German mindset was to keep the new coolant the same colour so that the mechanic knew it would be "compatible". Until 1994 the only coolant in use was the IAT brew and colour meant nothing. Apparently the US used green as it was easier to see rust in it from cast iron blocks- thus the mechanics knew to change it as and when they saw such. With alloy blocks and heads this became irrelevant. Post 1994 as and when more coolant types emerged a need to standardise colours was then perceived to be necessary. Doubtless you will have heard that "Dexcool" if contaminated with the wrong coolant type [i.e. IAT] can and does form a gelatinous gunge that will terminally constipate any engine cooling system. Obviously your motor did not experience this. The water pump volute is as clean as a whistle. On the photos you have already posted take a look at the transfer passages in the head- all of them [open or closed off] are as clean as a whistle- clearly no problems with the type of coolant the motor was using or its condition.

worf928

Necromancy applied to this thread...

The CRP online catalogue (http://showmetheparts.com/crp/) is a nice one-stop-shopping site for figuring out which Pentosin fluid you can use for whatever Porsche you need fluids. It has cross-references to Porsche part numbers (at least for the current models.)

For the 928 it recommends... For coolant.... <drum roll>

Pentofrost NF.

I can't say I agree with the motor oil recommendation though.

And Howard Wright disagrees with the site's power steering fluid recommendation for his racks and pumps in favor of the latest stuff.

ador117

Bonjour,
After 25 pages... my understanding is that pentofrost NF is the preferred coolant, in particular for a rebuilt engine...
But it is not available in Europe... can't be shipped... So I will have to bring back about 8 liters in my suitcases...
Pfff...

FredR

The 2nd generation coolant intended for our 928's is BASF Glysantin G-48- a hybrid OAT formulation and should be readily available to you in France.

As I could figure out Pentosin either make it under license from BASF or buy it from them filled in jugs with their label on it. VW sell the same stuff and call it G11 and charge you roughly twice the unit price and Porsche do the same and charge you roughly three times the unit price for the luxury of being supplied in a Porsche labelled bottle [that appeared to be the case 5 years ago no idea what the situation is today]..

I have no idea what the price of Pentosin is but I suspect it will be competetive with G48.

ador117

Bonjour FredR, and all,
It does not look as simple to me. I just try to stay conservative.
Nobody in any thread I read on the subject had something to say against the Pentofrost NF. I love this kind of consensus!!!
I'm rebuilding my engine and some people, as Greg, recommend to put this in rebuilt engine. My understanding is that it is what he is doing for his engines. He is a professional so he needs to get minimum issues in service. I love minimum issues as I have too much issues to face everyday!!!!
I used to put the liquid I think could be good, no matter the generation... I get my heads slightly corroded... the last coolant that was in the car before the head gasket failed was G-48 (diluted at 40% + water vetter for track use).

I don't want to insinuate that G-48 is not good... but others like worf928 would prefer G-40 instead... and Greg, if I understand correct, recommend this only on engine with to known history... and my experience is not the best ever even if I think she is not representative (I do not know what was in the car between the time is was no more maintained by Porsche and I did put in it yellow stuff inside from 2012 to 2018. Since 2018 I have blue stuff in.

So I reseach more about Pentafrost NF : if it could not be shipped to France and I did not find it in Europe, the only explanation is that there is something in it that is not IAW REACH regulation.
This regulation is to make Europe use product that do not work anymore... Europeans are frighten of everything... "RISK" : Oh my god!!!! please forbid something quick quick quick!!!!! oh yeaaaa it is forbidden... now I'm safe!!!
This is European democracy...

So I went to MSDS/FDS and it looks like that there is a product called "tétraborate de disodium pentahydrate" in our FDS that looks to be forbidden in Europe. Should be available in 2014, the last FDS I found was dated 2014... but should have been forbidden since. I will work on that and verify.
In your MSDS there is something called "Disodium tetraborate (boric acid, disodium salt)" and it is not identified for you as a dangerous staff...

So, If there is a significant additive in Pentafrost NF that could contribute to the consensus that it is the best product for our cars... could be something important...
And if Porsche coolant use to work... and does not work anymore... maybe it is because this additive as been removed from their stuff? this could explain why... maybe... maybe not...

Just one more brick to this wall... everybody will be free to keep it or to throw it away...
Have all a great day,

Darklands

I use G48 ReadyMix for Porsche before 1995.

GLYSANTIN® G48® Concentré | GLYSANTIN®

FredR

Karsten,

Given Porsche did not approve G48 for use in their early generation water cooled models until 1998 that would take some doing!