'82 S3 N/A - HOT RUNNING PROBLEM

[Bob Silk]

I own a 1982 S3 N/A which runs very poorly when hot.

 

The symptoms are as follows:

 

1) Starts from cold relatively easily and picks up well on the throttle with no flat spots.

 

2) Continues to run well up to temperature and also when the fans cut in, albeit as the temperature rises the idle drops from 1000 revs to about 850 revs.

 

3) Turn the engine off and leave it for 5 to 10 minutes and it is then difficult to restart, runs poorly and eventually dies.

 

And so something is breaking down in some way due to heat.

 

I have checked and or replaced the following:

 

a) New speak plugs.

 

b) New distributor rotor arm.

 

c) New electronic ignition module (Accuspark).

 

d) Distributor cap, HT leads and plug caps are less than two years old during which time the car has covered less than 2000 miles.

 

e) New ignition coil and ballast resistor.

 

f) New inlet manifold gasket.

 

g) Carburettors ultrasonically cleaned.

 

h) Carburettors balanced with Morgan Carbtune.

 

i) Compression checked 170 psi for each cylinder +\- a couple of psi across the four cylinders and so I do not think that the engine has worn piston rings, cylinder bores or a blown head gasket (no “mayonnaise” in the oil filler cap).

 

j) Vacuum hoses from the inlet manifold do not seem to be leaking.

 

k) New fuel filter.

 

So, I have run out of ideas!

 

Question - what have I missed?

 

Bob Silk

 

 

 

 

3 deleted. Ctrl + Z to Undo.

 

[marode]

Have you checked your float hights? When you get the trouble, is there enough fuel in the carbs? I would have a look. There should be 27mm of fuel in there from my memory (could look up the exact figures later). I wouldn't be too concerned about the fact that the engine is difficult to start when hot and after 10 miuntes, that´s pretty normal.

 

 

I´d really like to know what you have missed as I am in a very similar state. I get loud missfires when the engine get' to its normal operation temperature. Esprit S2. Engine runs perfect from the start (ok after about 30sek). When water reaches arround 85 degrees, it starts to cut out followed by very loud missfire. My guess is it`s missing some beats (I can feel and hear that before), then collects unburned fuel in the hot exhaust which is then ignites with a loud bang.

I am also running out of ideas and will remove the head next and get it crack tested - But I´d really love to avoid this.

So far done:

Carbs ultrasonic cleaned,

new fuel tanks, fuel lines / filter

new fuel pump

Lumenition module checked and optical sensor replaced

rotor arm replaced with red rotor arm 

Ignition set (correct)

Magnecetor ignition cables

spark plugs replaced 

compression test : (1-4) 185psi / 185psi / 160psi / 185psi

 

Also, any ideas welcome.

Cheers, Matthias

 

[jonwat]

1 hour ago, marode said:

I get loud missfires when the engine get' to its normal operation temperature. Esprit S2. Engine runs perfect from the start (ok after about 30sek). When water reaches arround 85 degrees, it starts to cut out followed by very loud missfire. 

Sounds like your ignition coil, you've not mentioned it in your list. The way to check is next time she starts misfiring pull over & grab hold of the coil. If you then scream "feck me that's hot" then it needs replacing. ☺

[ekwan]

8 hours ago, jonwat said:

Sounds like your ignition coil, you've not mentioned it in your list. The way to check is next time she starts misfiring pull over & grab hold of the coil. If you then scream "feck me that's hot" then it needs replacing. ☺

Make sure your fuel lines are not routed where it could be collecting heat. Fuel vaporising in the lines would cause a vapour lock, resulting in fuel starvation. The exhaust pop before the engine cuts out is a typical symptom of fuel starvation. Obviously, also check your fuses and the state of your fuel pump too. Often, resistance build up along the electrical connections and heats up due to electrical resistance, before giving up, only to restart again when it cools down.

[Trevsked]

Are you running a standard intake system? If you have filters bolted straight to the carbs then that’s usually the problem as it will be taking in hot air from the engine bay.

 

Trevor.

[marode]

Hi John, Trevor and others. Sorry for not responding, I was off for holiday. Did a +2500mls tour to and around the Bretagne in my 1967 Ford 20M P7 Coupe, which (as usual) has shown no faults at all - off topic... just a remark.

With the Esprit: I forgot to list an ignition coil swap. No efforts. Also I am running the standard intake system. I forgot to mention another frightening issue. I have mysterious water loss - I mean the Esprit has. After a few short runs (long runs don´t work out anyway since ages) there is like 1/2 liter of water missing. I recently replaced ALL hoses and (therefore) also the intake manifold gasket. Radiator is ok.

Concerning heat: yes, I also do believe heat could cause the fuel to vaporise. It is EXTREMELY hot under that engine-cover when the issue appears. Though water temp is shown as 85-90° ok.

My worry is I may have a head gasket failure or cracked head as I am running out of ideas. I mean fuel supply should be ok after all the work done, ignition is ok - what`s left?

Hey, and also: what about Bobs original question! I didn´t want to hijack his thread, just thought my fault could be somehow related.

[jonwat]

16 hours ago, marode said:

My worry is I may have a head gasket failure or cracked head as I am running out of ideas.

Get yourself one of these to test your coolant for combustion gasses. 

[marode]

thanks for the hint. I already did that last year - the test fluid I used is to investigate the air above the coolant. And it actually discolored to slightly green, which means I have collected CO2. I wanted to repeat the test after a "failure run" to be sure. I mean hope dies last... I was thinking it is sort of stinky in the engine bay anyway. Now I have already read reports about "is it possible to pull the head without removing the engine..." because it would somehow make things easier for me, I wouldn't have to do the job in the workshop of a friend and block the space for god knows how long.

 

[jonwat]

7 hours ago, marode said:

Now I have already read reports about "is it possible to pull the head without removing the engine..." because it would somehow make things easier for me, I wouldn't have to do the job in the workshop of a friend and block the space for god knows how long.

Undo the exhaust side engine mounts, the gearbox mountings & exhaust, this  will allow you to jack up the engine into a vertical position. Makes removing the cylinder head much easier. 😀

[ekwan]

On 20/04/2019 at 20:17, Bob Silk said:

I own a 1982 S3 N/A which runs very poorly when hot.

 

The symptoms are as follows:

 

1) Starts from cold relatively easily and picks up well on the throttle with no flat spots.

 

2) Continues to run well up to temperature and also when the fans cut in, albeit as the temperature rises the idle drops from 1000 revs to about 850 revs.

 

3) Turn the engine off and leave it for 5 to 10 minutes and it is then difficult to restart, runs poorly and eventually dies.

 

And so something is breaking down in some way due to heat.

 

I have checked and or replaced the following:

 

a) New speak plugs.

 

b) New distributor rotor arm.

 

c) New electronic ignition module (Accuspark).

 

d) Distributor cap, HT leads and plug caps are less than two years old during which time the car has covered less than 2000 miles.

 

e) New ignition coil and ballast resistor.

 

f) New inlet manifold gasket.

 

g) Carburettors ultrasonically cleaned.

 

h) Carburettors balanced with Morgan Carbtune.

 

i) Compression checked 170 psi for each cylinder +\- a couple of psi across the four cylinders and so I do not think that the engine has worn piston rings, cylinder bores or a blown head gasket (no “mayonnaise” in the oil filler cap).

 

j) Vacuum hoses from the inlet manifold do not seem to be leaking.

 

k) New fuel filter.

 

So, I have run out of ideas!

 

Question - what have I missed?

 

Bob Silk

 

 

 

Try disconnecting the rev limiter

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