Awful running when hot/getting too hot.

[Arya2.0S]

My car runs like utter ass when it gets hot.
The temp gauge gets half way and its starts to cough and splutter and wants to constantly stall when sitting in traffic.
Up until the temp gauge gets that high however, she runs like an absolute dream.
She isnt over heating, theres no steam coming out from under the bonnet or anything like that, and the temp gauge doesn't seem to go higher than a little past half way (though ive never let it run for long enough to find out).
Thermostat was tested as working perfectly fine just a couple of months ago, and i had this problem before that as well.
Thing is the entire engine has been swapped out for a totally different one yet i have the exact same problem as before!
New (second hand from Capri gear) viscous fan was installed, as well as an electric one to try and help it but nothing has helped so far.
Only thing thats not been changed is the radiator, this is the same old rad the car had with the previous engine.
It has a few lines of missing "fins" (not sure what they are called), could this old rad just not be up to the task anymore and is allowing it to get hot?
Thing is i didn't think half way up the temp gauge was that bad, but it seems to kill the engines' performance and ability to run smoothly (or at all, it will die if i dont blip the throttle) on mine.
When it gets like this i do notice the oil pressure gauge dips from where it usually sits firm at half way to just under. As its about to stall it falls to a quarter of the way up, and then rises again back to normal when i rev it. Could this be a symptom of something?
I have ordered a new uprated aluminium race-spec radiator to replace the tired old worn one, even if this doesn't fix the issue i needed a new rad anyway and it only cost £20 more than a brand new OEM spec one. It'll probably be overkill but hey, why not? At least its one possible symptom ticked off the list, but if it doesn't fix it what else could it be?
Water pump maybe? How would i test it?
And so the ongoing saga of classic car ownership continues...

Thanks in advance laddies.

[fordperv]

By any chance did you use your old carb on your replacement engine? If so is it a water fed choke one? Could be that the choke unit is playing up

[Arya2.0S]

By any chance did you use your old carb on your replacement engine? If so is it a water fed choke one? Could be that the choke unit is playing up

Yes we did, its a twin choke Weber...i think its one of these: http://www.fastroadcars.co.uk/store/ind ... uct_id=150.

The choke works perfectly on a cold morning though. I pump the pedal twice and start her up and she revs high until shes warmed up, then idles as normal until the engine gets hotter and the problems start.
Though ever since the weather has been hot shes not done this on first start up but figured this was normal just due to the time of the year since the engine hasn't got to work as hard to start when the outside temperature is already so warm, though i could just be talking out of my arse as i dont have a clue about these things.
Are these choke units inspect-able/replaceable?

[Jasonmarie]

One thing I do remember is if your running unleaded and the head has not been done you could have a exhaust valve that's tight or timing is out . As mine did that back in the 90s .
Only a thought but I guess you have done all that already .

What with the wheel wobble and getting hot sounds like you need a pint and things to start playing ball , but your right it's the fun of owning a classic .

[Peter-S]

Have you tried a different fuel pump, sounds like a fuel flow issue.

[Paul G]

I don't think it's necessarily a choke problem. It could be due to fuel vaporisation as it's been very hot today. Perhaps try a higher octane grade of fuel. Also is the insulator plate fitted between the fuel pump and the block?

More likely it is something in the carb like a bit of dirt in the idle jets or the float in the float chamber needing adjustment. I've found a couple of you tube vids to show you how to check these.

https://www.youtube.com/watch?v=u5C-paKEh-Y

https://www.youtube.com/watch?v=KnXpyJkJuYE

Also, here is a Weber trouble shooting guide FYI.

http://www.webercarbsdirect.com/v/vspfi ... 0Guide.pdf

Finally, just try slightly richening the mixture(1/8 turn out - no more) and turning up the tickover by 50-100 RPM.

P.S. Peter is right, it could be that your fuel pump is getting tired and not pumping sufficient to overcome the vaporisation.

[Mr B]

Hi mate,

Quick question are you running points and condenser or electronic ignition? only asking cos I had this exact same problem on one of my cars and it turned out to be a bad condenser - engine cold/warm fine but once really hot it would cough, splutter, cut out and not restart until it cooled making me think it was carb,fuel vaporisation etc but the condenser was the culprit and it was brand new as well .....
Coil on it's way out can cause this too

Wayne

[pbar]

It could be due to fuel vaporisation as it's been very hot today.

Surely though if that was the case Paul, then all of our cars would be behaving the same way?

[Paul G]

It could be due to fuel vaporisation as it's been very hot today.

Surely though if that was the case Paul, then all of our cars would be behaving the same way?

That's true Paul, Capris aren't known for it are they. Really had it bad when I had a P6 Rover V8, had to insulate all the fuel lines and fit and electric pump with pressure reg on that!

As I said in the original post, It's more likely to be a carb fault or as someone else had said something electrical getting too hot. Like all things it's easier to do a diagnosis with the car in front of you.

[pbar]

Yes, my car was behaving very similar a little while ago (not specifically when hot though), turns out it was crud in the carb just as you say. I blew through the idle circuit with compressed air, that cured it.

[Paul G]

Yes, my car was behaving very similar a little while ago (not specifically when hot though), turns out it was crud in the carb just as you say. I blew through the idle circuit with compressed air, that cured it.

That's the usual problem with rough idling on any carburettor car.

[pbar]

It's good to know that is Paul Certainly the first place I shall look if I have any similar problems again.

[Arya2.0S]

One thing I do remember is if your running unleaded and the head has not been done you could have a exhaust valve that's tight or timing is out . As mine did that back in the 90s .
Only a thought but I guess you have done all that already .

What with the wheel wobble and getting hot sounds like you need a pint and things to start playing ball , but your right it's the fun of owning a classic .

I know right? About time i had a bloody break. To be fair though, ive had this problem for a long time (even before the engine swap) ive just never got around to fixing it since i dont usually drive the car for long enough when doing errands around town to let it get hot enough to start having problems, but nowadays im doing a bit more driving its starting to become a major pain.
I do believe i have the later head, it has 87 date stamp on it so its possibly already been converted, but like i said i had this exact same issue to the T with the old engine and head too which leads me to believe its something external (i.e. bolted on to the engine from the old one) thats the issue.

Have you tried a different fuel pump, sounds like a fuel flow issue.

Thanks. No not yet. It works perfectly until it hits that mid way threshold in temperate though, so if it was the fuel pump would it not be a problem 100% of the time? Its literally only as it hits that exact spot on the temp gauge (around half way) and that is the only time it starts causing a problem. Up until then it runs perfectly.
I'll look into a new fuel pump just in case since they arent too expensive, thanks.

I don't think it's necessarily a choke problem. It could be due to fuel vaporisation as it's been very hot today. Perhaps try a higher octane grade of fuel. Also is the insulator plate fitted between the fuel pump and the block?

More likely it is something in the carb like a bit of dirt in the idle jets or the float in the float chamber needing adjustment. I've found a couple of you tube vids to show you how to check these.

https://www.youtube.com/watch?v=u5C-paKEh-Y

https://www.youtube.com/watch?v=KnXpyJkJuYE

Also, here is a Weber trouble shooting guide FYI.

http://www.webercarbsdirect.com/v/vspfi ... 0Guide.pdf

Finally, just try slightly richening the mixture(1/8 turn out - no more) and turning up the tickover by 50-100 RPM.

P.S. Peter is right, it could be that your fuel pump is getting tired and not pumping sufficient to overcome the vaporisation.

Cheers. Thanks for the links. I do know how to richen the mixture and tickover so might try that first, but thats not gonna stop the temp gauge rising however which is the only time it starts having problems. Dirt in the carb would mean bad running all the time would it not, not just when it gets hot?
Regarding the insulator plate, i wouldn't know. What does it look like and i can check.

Hi mate,

Quick question are you running points and condenser or electronic ignition? only asking cos I had this exact same problem on one of my cars and it turned out to be a bad condenser - engine cold/warm fine but once really hot it would cough, splutter, cut out and not restart until it cooled making me think it was carb,fuel vaporisation etc but the condenser was the culprit and it was brand new as well .....
Coil on it's way out can cause this too

Wayne

Hi, yes i am running electronic ignition. Your problem sounds exactly the same as mine, this is gonna show how little i know about these things but if i have electronic ignition do i still have a condenser?
I've often wondered if the coil was dodgy because i did used to have a problem with the engine dying after turning on too many things (revs would slowly die with each new electrical thing i turn on until it died completely, battery and alternator are working perfectly though as they've been tested with a multi meter), but since having the timing adjusted a little bit this hasn't been such an issue, though it still does pop up from time to time but usually this heat related issue rears its ugly head first so its hard to tell whats triggering what at that stage.

[pbar]

Dirt in the carb would mean bad running all the time would it not

Not really no, it can be very intermittent and random. It was with mine, I simply took out the idle circuit jet/screws and blew through both ways with compressed air (you can buy it in a can), and that solved it. That's a technique shown on that Weber guide also which Paul G linked to (Section H - cleaning the idle circuit).

[Arya2.0S]

Dirt in the carb would mean bad running all the time would it not

Not really no, it can be very intermittent and random. It was with mine, I simply took out the idle circuit jet/screws and blew through both ways with compressed air (you can buy it in a can), and that solved it. That's a technique shown on that Weber guide also which Paul G linked to (Section H - cleaning the idle circuit).

Hmm, I'll give it a go then, though this issue isn't intermittent it's 100% predictable, but only when it gets too hot, though I still don't think half way up the temp gauge is "too hot" personally, but then again she's old and fussy lol.
Might be automotive menopause?

[Arya2.0S]

Just cleaned out the jets. I didn't see any signs of dirt in them but i cleaned them anyway and ran the engine to get it up to temp where it usually starts playing up and it seemed ok, but i dont think thats accurate as it was just idling and stationary, it usually doesn't start showing problems until you're out on the road and in traffic (fussy bugger).
I did increase the idle speed a little bit too though, so maybe that has infact helped? We'll have to wait and see. Once i get a new rad fitted i'll test it properly and go from there.

[Mr B]

Hi Arya,

As you have electronic ignition you have eliminated the condenser, but your coil could still be the problem, when your car starts it's shit do the revs pick up and drop again whilst she is idling?

Wayne

[Mc Tool]

How good are your plug leads ?

[Arya2.0S]

Hi Arya,

As you have electronic ignition you have eliminated the condenser, but your coil could still be the problem, when your car starts it's shit do the revs pick up and drop again whilst she is idling?

Wayne

No when shes on choke and even afterwards she runs perfectly, its literally only when she gets too hot she starts having problems.

How good are your plug leads ?

Brand new no more than a month or two ago. They are Accuspark ones.

[Arya2.0S]

An uprated "race spec" aluminium radiator has fully cured this issue. So looks like it was just an overheating issue after all.
Thanks everyone for your help and suggestions.