504 dies under brakes

Ray Bell

Ray Bell

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Burpengary and Murrumburrah, Qld and NSW
I think we've struck this before, but it's on again...

The square port 504/505 setup... repeatedly I come up against these engines developing a tendency to stall under brakes.

They just stop... now I know this isn't a real problem for actual drivers... we know how to heel and toe, but the useless ones to whom I lend my cars are complaining left and right.

It's not a matter of anything having been done to the engines either. Certainly not in this latest case... it's just being driven around and it's developed this tendency. This has been the case sometimes in the past... though not always.

I really don't want to get a pile of 'I think it might be this...' answers either... I know someone will know for sure exactly what it is... please, that someone, let me have the definitive answer.

What I mean by that, please don't say, "Well, on the Renault 16 when that happens..." or "maybe somebody has changed the float level..." or "when the last service was done..."

None of these apply. This is a this very model specific problem... time after time it hits one of these cars in my ownership... and for once I know for sure that nothing has been touched this time. Nothing at all...
 
have you checked the valve on the brake booster ?
i had a 604 once that under brakes the car would stall
it was traced back after all checks were done to the booster valve
what it was effectively doing was pushing vaccuum back into the inlet manifold (even though the brakes stilled worked well) and the car would die
or so i was told that was what was happening
i replaced the valve with another and it never did it again

i realise that you are asking why is it only the square port head cars that have this problem but i have had the same with a 604
 
one of my old 504s did this, and it took me ages to figure it out. But it wasnt a square port, it was a '77 round port twin carby. (but I did convert it to an ealier solex twin throat later on )

From what I remember (this was quite a while ago...) it was down to float level issues in one of the carbs. If my memory gets better, I will let you know :mallet:
 
Older than the square port one is now... it's a '76 model (or the last one is) and I last used it regularly two and a half years ago.

The 1980 model that's presently giving the problem is therefore about 18 months newer. The Familiale also had the problem three and four and five years ago, and it's a 1982 model.
 
Ray Bell said:
Older than the square port one is now... it's a '76 model (or the last one is) and I last used it regularly two and a half years ago.

The 1980 model that's presently giving the problem is therefore about 18 months newer. The Familiale also had the problem three and four and five years ago, and it's a 1982 model.
Click to expand...

it can't be just a square port thing
if it was then how many 505's would be having the same trouble ?
is the car manual or auto ?
 
There wouldn't have been any point in posting this if they hadn't all been standard and all been the same...

They are... bog standard.

I will look at that brake booster thing when I get to Queensland, but I really need to know before I get there what other prospects there might be... and again, only from people who've had problems with this same setup and have found the answers.

I will only have a couple of days up there, and it has to be fixed before I leave.
 
Well i have had this problem with my car.

For me its the brake booster and timing.

I replaced my brake booster and the problem went away:)

shobbz
 
Thanks... but was your booster still working?

My first plan of attack will be to put a one way valve (ex-Datsun) in the booster line.

Yours is, of course, a different model... but thanks for the info. Did you drive this car (the green one) when you were at my place, by the way?
 
Yes my booster was completly stuffed. Loose as anything

Don't think that I drove the green one.

shobbz
 
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