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Is just blanking it the wrong thing to do. Obviously at the block and at the Y pipe. Or is looping it better. Either way is just as easy.
Not Greg, but I think it's ok to just blank it.
I know that there is a 'common wisdom' that 944 heads should be looped, because without the heater core loop, the head has a 'dead end' where coolant can't circulate.
How it handles having the heater control closed I do not know. I've asked that question, but never gotten an answer.
Personally, I'd loop it if it's just as easy. Make sure that the coolant is circulating through the heads completely.
But that's me.
I know that there is a 'common wisdom' that 944 heads should be looped, because without the heater core loop, the head has a 'dead end' where coolant can't circulate.
How it handles having the heater control closed I do not know. I've asked that question, but never gotten an answer.
Personally, I'd loop it if it's just as easy. Make sure that the coolant is circulating through the heads completely.
But that's me.
The coolant is not "dead ended" in the 928 heads, it simply flows across the cylinders and then exits the water bath through the open apertures in the gaskets/heads and then back along the cylinder head and then into the radiator.
The heating loop is a parallel flow path and when operational with the heater valve open heat is removed in the core instead of in the radiator. Take out the heater core and leave the valve open inadvertently is not a good thing as it them becomes a bypass without removing heat which is why I uncouple the actuator arm and wire the disc valve in the closed position. Equally there is nothing wrong with leaving two dead ended stubs- I just found it easier to do it the way I did.
Is just blanking it the wrong thing to do. Obviously at the block and at the Y pipe. Or is looping it better. Either way is just as easy.
I wouldn't block it off...even though it is only the one head.
On race engines, without a heater, I add a "vent line" to the highest point at the rear of each cylinder head to remove any possibility of air being trapped.
I "grew up" around American V-8's, where trapped air in the back cylinders was a problem in cooling the rear of the heads.
American V-8's route their coolant the same way as a 928 engine, so I just took those early lessons and applied them.
As these 928 engines age, the head gaskets deteriorate, and "extra" holes appear in the gaskets, it becomes even more important to encourage coolant to flow to the rear of the heads/back cylinders.....not to be blocked by a huge air bubble that can never leave.
I see a tremendous amount of 928 engines apart...and the increased heat (in the rear cylinders and at the back of the heads) is becoming a huge problem.
I've even seen GTS engines with burned exhaust valves in the rear cylinders.
A puzzling comment from your good self- as someone who had to seal highly toxic well heads at 10,000 psig for a living to avoid killing everyone within a 40 mile radius [amongst many other things] I think you can safely assume that I understand the heater core needs to be isolated.
The OP asked how it was done and I explained in principle how I did it and why- in my case it was to preserve the heater core as I never use it. The layout on the RHD models is somewhat different but the principle remains the same. If there is any confusion I will happily post a pic of what I did.
Excuse me. Try to relax...I'm not the enemy. We're all here, presumably, trying to lend people a hand.
From your prior posts, it seemed that you were still routing coolant (and thus pressure) to your heater core.
I was simply pointing out that the OP's problem was a leaking heater core and that isolation with pressure would allow it to still leak.
And I had absolutely no idea that sealing toxic well heads at 10,000 psi had anything to do with a leaking 928 heater core...didn't seem like remotely the same thing.
Excuse me. Try to relax...I'm not the enemy. We're all here, presumably, trying to lend people a hand.
From your prior posts, it seemed that you were still routing coolant (and thus pressure) to your heater core.
I was simply pointing out that the OP's problem was a leaking heater core and that isolation with pressure would allow it to still leak.
And I had absolutely no idea that sealing toxic well heads at 10,000 psi had anything to do with a leaking 928 heater core...didn't seem like remotely the same thing.
Greg,
You will have to excuse my somewhat dry but well intended British sense of humour. A pressurised system is pretty much the same irrespective of the different ends of the technical difficulty scale the only difference being the extent one goes to to ensure containment. What I was alluding to was the notion that "I would not have isolated the heater core", in professional terms, that is a bit like saying you do not know how to do bearing clearances and that had me in stiches albeit quite understandably you have no background information to understand such.
As I initially wrote in my post I remain puzzled as to what you read that could possibly infer that I did not isolate the heater core but being the wise soul that I am, I remain open minded as to other possibilities of interpretation of what I wrote.
You will have to excuse my somewhat dry but well intended British sense of humour. A pressurised system is pretty much the same irrespective of the different ends of the technical difficulty scale the only difference being the extent one goes to to ensure containment. What I was alluding to was the notion that "I would not have isolated the heater core", in professional terms, that is a bit like saying you do not know how to do bearing clearances and that had me in stiches albeit quite understandably you have no background information to understand such.
As I initially wrote in my post I remain puzzled as to what you read that could possibly infer that I did not isolate the heater core but being the wise soul that I am, I remain open minded as to other possibilities of interpretation of what I wrote.
No big deal...certainly not worth cluttering this thread with.
But for clarification....I got really confused at your post #2 and post #5, when you were trying to explain why the heater control valve was important to leave in, how you wired it shut, and disconnected the vacuum.
Just didn't understand the point of doing all that, instead of just removing the valve.
Now I think I understand that you were trying to keep water flow from freely circulating though the bypass "loop", all of the time, which could be a real issue, given the current condition of most cylinder head gaskets.
It's certainly no easy job! As your A/C is not working at the moment, don't get it fixed until you have done the heater core would be my advice.
Some years back I replaced a heater core in m '81 model, because it was leaking.Even with the dash and console out it's still a real juggle.
As Dr Bob said, it's one of the first things to go in the car.
Certainly on my current project, it was the first thing to go in after the suspension and with a completely stripped cabin, it's tight.
On the good side, your ca is in its late thirties, so with the A/C 'factory' out you can check/replace all the pesky vacuum pods and their lines and all the old foam seals that have turned to dust. Plus check and lube the blower.
You'll be set for years!
01-18-2021, 11:54 AM
