911 3.2 heat exchanger question

james280779 · 09-01-2014, 06:09 PM

Hey,

I have had my 911 a few years now but first time I have felt the need to ask a technical question.

I bought the car in the UK and it is now with me in the Tropics of North Australia.

I took it to my local mechanic who I trust considerably as he is also a good friend for new head gaskets and a few other engine jobs.

The engine is out of the car and it has got a few rusty bits- he has employed another fellow who he states (knows these engines and cars inside out). I have chatted with him and he does know them extremely well.

However, a few things need replacing and one of them is the heat exchangers which have rusted through. His advice to me was to not bother. He reckons as its 30 degrees minimum every single day its simply not needed. They only heat the car interior and accelerate the engine warming up process which just isnt required here.

His advice is to ditch the heat exchangers and save weight / cash and spend the money on something else to further improve the car.

I have no intention of selling the car anytime soon so is this a possibility? I can always add them later when I move South if its viable. I cannot find any reference to this on the net so I am dubious about doing it.

thanks

james280779 · 09-01-2014, 06:12 PM

The engine is also having a complete top end rebuild now too as I decided I might as well have it done while out. The bottom end is in very good condition so doesnt need attention.

james280779 · 09-01-2014, 08:24 PM

Ok have just got back from the mechanics.

Compression testing all good, timing chain and guides in great condition as is just about everything else. Mechanic told me the engine has been rebuilt fairly recently (compared to the life of the car)as was told to me by the previous owner (he had however lost the folder detailing so I didnt pay a premium). He stated 2005-2007 it was rebuilt.

The problem for the leaking heads has been established as the fact there was never any head gaskets used. Or any kind of substitute- literally bare clean metal on bare clean metal. The problem only arose when I used thinner oil than I should have done.

Has anyone heard of this before? I have been using it for three years daily and if correct its nine years without gaskets????

Dueller · 09-02-2014, 05:53 AM

No head gaskets? Hmmmm....never heard of that. And compression is ok? Did they do a leak down test.? What exact problems are you experiencing after us in "too thin oil"? How thin was it?

As to heat exchanges you will lose defrost/devising function. May not be a big deal in your clime. Several folks have eliminated heat exchangers for headers. Just depends on your needs.

Dueller · 09-02-2014, 05:54 AM

No head gaskets? Hmmmm....never heard of that. And compression is ok? Did they do a leak down test.? What exact problems are you experiencing after using "too thin oil"? How thin was it?

As to heat exchanges you will lose defrost/devising function. May not be a big deal in your clime. Several folks have eliminated heat exchangers for headers. Just depends on your needs.

911pcars · 09-02-2014, 09:14 AM

Yup. 3.2 used no head gaskets.

As for a direct replacement for a rusted out exhaust system, many owners install SSI/Dansk heat exchangers (thick flange version). They will provide heat and possibly some performance improvements. Some oil line mods required. The twin outlets will also provide more muffler options for improved sound. Depending on your location, there may be exh. emission specs to address.

However, at the 3.2 threshold, the 1.5" tubes (1.375" ID) may be slightly restrictive. The "ideal" seems to be 1 7/16" tubes (1.5" ID), typically found on exhaust headers (w/o heat) or with 993 heat exchangers which require inlet flange mods as well as fitment to muffler.

Sherwood

fiminod · 09-02-2014, 09:32 AM

North Australia - 30c is about 86f for us North Americans...and that's his minimum temperature...he doesn't need heat

Dueller · 09-02-2014, 09:38 AM

Learn something new everyday. ...last motor I was in was a 3.0...
That had headgaskets, right?

james280779 · 09-02-2014, 02:47 PM

Quote:

Originally Posted by Dueller

No head gaskets? Hmmmm....never heard of that. And compression is ok? Did they do a leak down test.? What exact problems are you experiencing after using "too thin oil"? How thin was it?

As to heat exchanges you will lose defrost/devising function. May not be a big deal in your clime. Several folks have eliminated heat exchangers for headers. Just depends on your needs.

The only problem I had after using thinner oil was a small oil leak started coming from (what I thought) was the head gasket. It was only minor so I didnt bother getting it done. Must be coming on two years now since it started- engine ran very well. Absolutely no other issues. Started getting worse about two weeks ago so I decided to get it done. I put in 0W-40 Mobil 1 synthetic. At least I know having run that for a while this is my only leak and when sorted she will be well lubed.

Compression is more than OK - it is pretty much spot on. My mechanic reckons the engine will be good for another 10 years provided its serviced regularly (which it is anyway) Car has a FSH from new and pages upon pages of receipts for work so I know its been looked after. I usually have it service stamped once a year and depending on how its being used I might service myself at six months.

I have literally never needed to defrost my window, I only wear jeans once or twice a year. Imagine florida weather but more humid between Oct-Nov. Thats pretty much the climate here.

Dueller · 09-02-2014, 02:59 PM

Lemme guess....this is the first time you used synthetic oil?

james280779 · 09-02-2014, 03:15 PM

Yes.

it was the first time Ihad it serviced, It was done when I bought it so a year later comes to service time.

Lesson learnt the hard way, I know now that I shouldnt have used fully synthetic but hindsight is a wonderful thing.

On the plus side I now know the engine is in great condition and I had no plans for that $2.5k anyway.

Richard Burns · Richard Burns's Garage

Hi James, I am going to assume that you are up around Darwin or similar. The humidity is going to be your biggest problem with standard heat exchangers. The best bet is to fit stainless steel heat exchangers as they will last a lot longer and if you get down to somewhere like Alice Springs and want to use your car early morning during winter then you will want heat.
Richard.

Chuck.H · Chuck.H's Garage

James writes:
>>I have literally never needed to defrost my window, I only wear jeans once or twice a year. Imagine florida weather but more humid between Oct-Nov. Thats pretty much the climate here.

It doesn't even get cool at night? I drove from Florida to Atlanta last nite... we're in the middle of the hottest time of the year, yet I still had my heat on for about an hour after a rainstorm dropped the temp briefly.

I have the SSI's with heater boxes, very happy with them.

Chuck.H
'89 TurboLookTarga, 381k miles

james280779 · 09-17-2014, 08:21 PM

Quote:

Originally Posted by Chuck.H

James writes:
>>I have literally never needed to defrost my window, I only wear jeans once or twice a year. Imagine florida weather but more humid between Oct-Nov. Thats pretty much the climate here.

It doesn't even get cool at night? I drove from Florida to Atlanta last nite... we're in the middle of the hottest time of the year, yet I still had my heat on for about an hour after a rainstorm dropped the temp briefly.

I have the SSI's with heater boxes, very happy with them.

Chuck.H
'89 TurboLookTarga, 381k miles

Occasionally at night for about a week it can get a little cool. Aside from the then no its almost as warm at night as during the day. It stays pretty constant. It also doesnt rain between March and xmas much- maybe a few times here and there.

In response to the other- why the hell would I ever want to go to Alice. Once was enough. Yes I am in Darwin.

I am rebuilding the car but obviously on a budget. I know I am in Darwin for the next few years so if I can get away with not replacing them for now then thats what I am doing. I would rather spend the cash on go faster bits. When I do eventually move south (probably QLD/ WA or SA) I will get new bits then.

I have just got a quote to have parts of the engine ceramic coated to make it look nice (very reasonable). He stated he can also do plastic almost any colour I want (not ceramic obviously). Has anyone got the air boxes etc colour coded rather than the standard black?

strikee · strikee's Garage

Put headers on it. You do not need heat exchangers in QLD.
+100

cameron.arnott · 09-18-2014, 04:26 AM

Hi James

I am also in Darwin

Drop me a line if you want to catch up at some stage.

There is a Porsche club up here albeit a bit small

I may have a line on some HE's but will have to investigate if they are still available. That said you sure won't need the heat while you live here…...

Cheers

Cam

james280779 · 09-18-2014, 03:05 PM

Quote:

Originally Posted by cameron.arnott

Hi James

I am also in Darwin

Drop me a line if you want to catch up at some stage.

There is a Porsche club up here albeit a bit small

I may have a line on some HE's but will have to investigate if they are still available. That said you sure won't need the heat while you live here…...

Cheers

Cam

Thanks Cam,

I noticed your details on the club emails, My car was spotted on the delivery trailer and I was tracked down - effective club running.
I have been to a couple of runs but with a baby its a bit difficult for me. I am going to delete the HE for now so dont worry too much- my heater blower motor went 2 years ago and I havent bothered replacing it so I have effectively not had heat anyway. I know I am here for a few years at least so its not a big issue- I just wanted to know if it was doable and if it would not damage the engine in anyway.