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MG Midget and Sprite Technical - Midget 1500 engine troubles all kind

Since sept 2008, I had overhauld the 1493 engine of my MG midget.
I had some troubles with cooling and oil pressure.
This seemed to be solved but I'm still encountering mysterious issues :

1. when driving and then hitting the brakes rather abruptly , my oil pressure drops from 60Psi till under 20 PSI ! And when coming to a full stop and waiting for several seconds at idle, the pressure resumes till 50. Could the reason be the centrifugal force which pushes the oil to the front in the oil carter ? Is there a solution ?

2. I have a lot of subpressure blowing at my cilindrehead, although all my pistons and segments are new so no wear can be possible.
I even did a pressure check at each piston. Normally this should be 9 Kg. I even have 10 kg per cilindre.
Is this subpressure normal for a 1500 engine ?

3. because of this high subpressure, oil is leaking out of my oil carter

Can anybody give me some advice on this ?

thanks

Gerrit
Gerrit

1
Yes a bafled sump
2/3
do you mean SUMP pressure?
did you try a leak down test?
have the rings bedded in properly?
is it running lean or rich?
is the HG ok?
Onno Könemann

Onne,

1. what do you mean by bafled sump ?
2/3 indeed sump pressure is high.
When opening oil lid at top of the valve cover
it blows very strong ...

No I did not perform a leak down test since the
test of the compression for each of the 4
cilindres gave a very high compression of 10
(factory default is 9 kg)

Rings were bedded properly. As for mixture, I'm
not sure, ignition plugs are dark brown colored so
between lean and rich..

WHat do ya mean by HG ?

thx

Gerrit

Gerrit

It is Onno ;)

a baffled sump has plates welded in from side to side with only smal spaces for the oil to pass
so under hard braking or acceleration it is harder for the oil to move quickly from front to back.
And so the oil pick up pipe always has a steady suply of oil

were the compression tests on a hot or cold engine?

Did you check the rings? because it does sound like blowby.
If you take off the sump the should not be a white look to the bottom of the bore (this indicates blowby)

HG= head gasket
They can crack to just a oil way and put extra pressure on the oil system
Onno Könemann

Onno,

I now understand. that kind of design I also had in mind to solve the problem but I was not sure if it existed.

Compression was measured on a hot engine.

I'll check the bottom of the bore when replacing the seal of the sump. I also need to straighten the sump edge. It often doesn't seal well when fastening it, it deforms especially on the edges where the holes of the bolts are..

Good point for the HG, it did not thought of that since it has been renewed also.

Many thanks for you expertise and advice, Onno !

Do you have a website ? Do you also own a Midget 1500 ?

grtz

Gerrit
Gerrit

I own a 66 midget (originaly a 1098 but soon to be a 1380)
But i have manny mg friends (including 1500 midgets)
And tinkering with old Brithish cars is a steep learning curve

no website from me but one from my favorite meeting places

www.mgworkshop.nl
Onno Könemann

Nice car !

I myself have a 1978 midget and a mgb roadster of 1974

I'm all into english and their traditions...




Gerrit

This thread was discussed on 11/04/2009

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