Huge Fuel Vaporisation issues.

[akuchanny]

Hi Guys, I have fitted an Aluminium Rad to my minor, It was a chinese one from fleabay, but apart from a small rad cap and a 1.3 bar rating to the cap that came with it it is light and very efficient. So far as I have had to massively adjust the electric fan as it wasn't getting up to temperature easily. It has brought up a new and very strange problem. The only change has been the rad, nothing else was touched in the process, and now the exhaust manifold excessively heats up, you can feel it through the floor, and the lower end of the gear stick also heats up excessively. This has meant that if I am in normal stop start traffic the car will have all the loss of power signs of vaporisation and the 1275 shudder's and stall's. Most apparent when ever you hit an incline.

I have fitted colder plugs and that has not done much, tried a quick temp heat shield which also helped a bit, but when trying to adjust the mixture the lcb is giving off so much heat that it can easily start to cook your hand with no contact after only a very short time running.

I don't think its a timing issue (may well be wrong) also don't think its a fuel mixture issue as when up to temp the car runs well. So am struggling to see what it could be.

Does anyone have any ideas, especially as before the rad change there where no issues of vaporisation at all with the car.

Andy

[MarkyB]

So it's over cooling and overheating?
I'm wondering why you had to adjust the fan at all.
Are you sure there is a thermostat fitted?

[panky]

Does the new rad sit any lower than the old one? If so then the coolant level will be lower in the engine and could cause overheating.

[akuchanny]

Hey guys, the engine temp is fine, nothing out of the ordinary there. A thermostat is fitted I think its a 88 degree unit put in when I rebuilt the block. The only over heating issue is the exhaust manifold. The radiator sits in the same position as the previous one, the only differences are the much lighter weight, the much cooler running temp and the top of the tank is a little smaller on the sides, although the hight looks the same.

The only reason I adjusted the fan was so it would cut in later giving the head more time to reach temperature.

could it be a detonation issue?

Andy

[panky]

Hmmmm, the fan controller shouldn't need to be adjusted as it will cut in on the temperature it is set to no matter what rad is fitted and if the new rad is that efficient the fan wold hardly be called into action, winding the controller up wont make it warm up any faster that's the thermostat's job. A tubular manifold will heat up in seconds, maybe some heat wrap might do the job - and have you checked you haven't lost the heat shield under the passenger floor.
Another thought, if the rad is working so well and the fan isn't cutting in all the while your sat there in traffic there is no air flow through the engine compartment so the heat just builds. Have you got a manual switch on the fan - try switching it on while stuck in a jam and see if that sorts it.

[delwin]

worth just checking you haven't got an air lock in the cooling system... this can cause some strange effects..

Dave

[bmcecosse]

Why did you change the rad? Put the standard/correct one back on!! Exhaust manifold overheating is almost always engine running too retarded - check the mechanical advance mech is working as it should - and the vacuum advance too....

[akuchanny]

Changed the rad as the original was toast, and this worked out cheaper (and in effect more cooling) than replacing it with a standard item. nothing was changed on the timing before or after the switch, but will check the timing and see if that can sort out any issues. Especially as now I have removed the temp heat shield the matter has become worse.

[les]

If it was ok before fitting this cheaper rad, it would be reasonable to suggest that the rad is your problem, get a real one!

[akuchanny]

A sound thought. I am not sure if the rad is the issues though, I think it has just exacerbated a existing underlying problem, I have had a few issues with the engine since its rebuild, and am going to swap it over (needs a clutch anyway) to see if this will solve some of the issues. I am looking into a heat shield and either thermocoating the exhaust or wrapping it. If the rad is only cooling at a improved rate, then the issue has to be somewhere else in the engine, if I do just swap back then that isn't really solving it but just covering it.

[bmcecosse]

Just how 'hot' does the exhaust get - glowing red ??? Or is this just all an 'impression' of heat you are getting???

[akuchanny]

The exhaust temp is noticeable, i would say it is on the verge of glowing red, since this issue it now sounds like it has blown either the exhaust or the manifold or the gasket. The first major vaporisation brake down after cooling for 30 mins, I started to adjust the carb with the engine running to see if I could solve the issue and after about 30 seconds the temp was so high I could feel my hand starting to cook, so had to resort to gloves. The temperature can also be felt through the floor and the gear box tunnel, as well as creeping up the gear stick. when the stick gets hot to the touch I know its going to start to cough and struggle with the now vaporised fuel.

If I get some time I will get a thermometer out and get a temp reading of the head, the block and the exhaust, so I can get some numbers up. I am guessing the first course of action is to check the timing, and the mixture, then set the idle and see if this has changed anything. I am struggling to see what else it could be.

Thanks

Andy

[tysonn]

Laser temp guns on EBay for a tenner.Very handy tool.You'll know the exact temps for sure!

[bmcecosse]

I suggested earlier that exhaust heat is generally due to running very retarded - have you checked the mechanical and vacuum advance mechs yet? Other possibility of course is that exhaust valves are either sticking open/burned seats or just incorrect gap setting. Set the gaps to 15 thou... and can you get a compression check?

[akuchanny]

I have a laser temp gun, that was the plan to use, will do a compression test when I get the time to, juggling another broken car at the moment as well. Haven't checked the mechanical advance yet or the valves, hoping they haven't burnt the seats as its a big valve head I only put on about this time last year. when I get the chance I will up date with what I find.


Thanks so far, I think the running retarded is the main candidate at the moment though but will check everything..... Although the engine is being pulled very soon, needs a new clutch, and as the front plate is not sealing well will probably be swapped over for another 1275 I have that is storage, with just a head swap, so a good time to check the valves and valve seats. But only when time and access to a engine crane is available.

Andy

[akuchanny]

Okay have set the timing to TDC it was quite a distance out. Have re set the fan and run the car for a while and the manifold is hitting around 200 degrees at its hottest, after about 15 - 20 mins at idle. Although traffic will be the real test!

Have also re set the idle and the mixture - idle is around 900 rpm and the mixture has been set by adjusting until it nearly dies and backing off until it sounds at its sweetest.

Only problem is now its running a bit like a pig. I will take it out for another run. But as this engine is being pulled, as the front plate is leaking I just need it to run without damaging the big value head on it so it can be switched over to another block, once I pick it up.

Although I do have a 1310 in pieces that I should get the bits for and get back in one piece.

I will take it for a run and keep you posted, any other ideas would be great. As I am sure going by my current luck it will not be such a simple fix

[les]

I may be getting this all wrong but I don't see why you are doing all this, if you intend to replace the engine. Why not concentrate on getting the replacement installed, at this rate all you are doing is risking damage to the parts you want for this other unit. I still think your rad is worth changing for a known original if you feel you must tinker with this temporary engine. Unless as I mentioned earlier, I'm missing something here.

[bmcecosse]

Are you sure the radiator is allowing enough water to circulate? It does seem to be at the 'core' of the problem....

[mike.perry]

You did not change the fan blades?

[bmcecosse]

Is the fan sucking air in - not blowing against the motion of the car... ???