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Engine Specific Info and Questions => IDI Engine => Topic started by: regcheeseman on January 30, 2012, 05:42:19 am
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My recently AAZ has a tendancy to run a bit hot, not overheating,just warmer than expected. Could this be a symptom of a slightly mis timed pump?
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retarded timing makes my engine run warmer than normal..
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My recently AAZ has a tendancy to run a bit hot, not overheating,just warmer than expected. Could this be a symptom of a slightly mis timed pump?
Have you adjusted the timing to suspect a mistimed pump?
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Do you always answer questions with another question?
Are you my wife?
retarded timing makes my engine run warmer than normal..
Thanks for that, confirms my suspicions.
It's a new built engine and I suspect that my pump is a bit retarded from optimum, however I advanced it a touch and it suddenly ran awful and wouldn't rev past 2000 rpm, so I put it back how it was and it still ran awful. I later found what was causing the poor running. (A coincidental fault)
The car went for it's first decent run (200 mile round trip) and just ran a bit hot all day - I suspected the timing may not be helping.
That's why my question was left open so as not to influence any replies.
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I am not your wife?
Yes I generally answer questions with questions. Only to further find out information..
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If you put brand new everything with close tolerances it could just be the extra friction from that. Will probably subside some with further break-in.
Could also go for a lower temp Tstat/Fan switch if its getting warm enough to make you nervous. And of course theres always the chance of loose tension on water pump belt sometimes too.
Hope it gives you good service for a long time.
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My recently AAZ has a tendancy to run a bit hot, not overheating,just warmer than expected. Could this be a symptom of a slightly mis timed pump?
My take on this is that it could just be that the engine is burning more fuel than the 1.6 for much of the time, but your cooling system is unchanged.
My thoughts on the timing v heating effect, is that out on the extremes of 'running' either retarded or advanced will waste more fuel, to get the same work done and heat the cooling and exhaust system more.
However, when operating around the 'correct' operating region advancing gives more heat to the cooling system, and retarding means slight raising of post exhaust valve heating, and so can be seen with slightly earlier turbo boosting.
There is a research paper on the internet that points to about 10 degrees ATDC as being the ideal place of peak chamber pressure, for work out [kind of makes sense f you think in terms of leverage 8); so I would think that at this point, the product of coolant losses and exhaust losses is a minimum; or is it the 'sum of' ;D
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My take on this is that it could just be that the engine is burning more fuel than the 1.6 for much of the time, but your cooling system is unchanged.
Yes, I'd thought about this, however a mate on exactly the same run with the same engine / radiator setup was running cooler.
He also has problems with the temp rocketing when the engine is worked hard - but that's just the case of the heat output of the engine exceeding the capacity of the radiator.
I've bought a new much bigger ally rad - hopefully that will sort it.....
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I checked the pump timing and surprisingly it was not a bit retarded as assumed but running 1.20 lift, I knocked it back to factory 0.95 setting and it struggled to start, coughing and spluttering even with cold advance pulled.
I've set it back to around 1.2 again.
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Both of my GTD's are as steady as a rock at 5/8ths on the guages. Seems VW never bothered getting them to sit at midway. Just a thought. ;)
If a man speaks in a forest and there is no woman around to hear him is he still wrong?
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If everything else is OK ,than in my case one injector is pissing and I got low mpg so no hard to get.
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1.2 seems a bit large. Maybe if that one injector was doing it's job the way it should your timing could bounce back to mid 90s and your starting issues would go away.
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yeh those timing numbers / results are odd.
If you rotate engine by the Inj Pump instead of Crankshaft you get an inflated number. But its only about .05 - .08 higher than actual.
I tested this before and posted results -
its somewhere in that range. iirc
Belt tension being too loose and using Inj Pump nut - those combined - could produce that much variation perhaps.
1.05'ish is supposed safe max on TD.
If you're rotating by crankshaft, and everything is dead on the button -
there are issues at hand.
I'd have the injectors spray tested and pop verified. imho
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could engine timing be off?
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At 1.2mm you maybe stressing the engine some, but it probably has tons of snap. I think running the cummins pump on mine at 1.28mm was the thing that was hard enough on the precups to make them want to fall out and one did. I would bump it up to 1.05 or so instead of the 1.2 and see if that helps. Your pump could be worn and not advancing like it should. I would suspect that the little hot you are running is from the 1.2 timing. When it was back a .95 it wasn't starting well, but did it run hot?
What is exactly hot? If you are going by the VW gauge I wouldn't worry, but if you have an aftermarket gauge that tells you exactly what you are running what is that number. 205F and under running it hard and I wouldn't be concerned.
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I'm running 155bar injectors instead of the 135s the pump had originally.
Internally the pump is spot on, the engine has just been rebuilt and the cam timing is bang on.
I was turning the motor on the cam pulley so that would equate to a small difference.
It is definitely running hot though - the previous 1.6 engine pegged the gauge at a fraction under the halfway mark. The 1.9 is fine until you start to push it. I've bought a performance rad and new low temp fan switch - hopefully that will keep it in check.
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Getting a rad for the car with a/c should give you the extra cooling.
For an injector to require your pump to be advanced to 1.2 ish, would require the injector to be opening with a way higher bar, say 200 ??? So I think not.
I suspect that he dynamic advance is lagging where it should be. Have you checked internal pressure v rpm, or even got figures for dynamic advance?
Have you or anyone come across a GTD operator's handbook?
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In the past i've read about how over advanced timing raises cylinder pressure (and heat). Can't remember the numbers / percentages.
But they go up fast. Its not a good environment.
There's most (if not all) of the heating symptom you have.
Is this the 1.6 block / 1.9 head engine you mentioned in another thread ?
Where it stands, i'd put the 135 bar Injectors in and have another go with it. I understand the advantage of a better/bigger radiator - but i think you need to get the cylinder pressure back down to deal with the heat at the source. Before other issues arise.
Between the internal pressure and the 135 bar Inj's something should reel it back in.
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pegged the gauge? so it was running 284F?
I really think the gauges in these cars create worry. If you don't have some type of gauge to be able to measure the actual number you maybe chasing your tail. I had a flat red bunny that would run 2 lines down from the red line on the gauge, but you could take and put your finger in the expansion tank. You couldn't hold it there, but it wasn't bubbling over or too hot. A number of how hot it is could give us a base to start with.
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no, not pegged the gauge as in maxxed out.
As in the needle sat at halfway and didn't budge, maybe creep up 1mm on a long hard climb
As soon as the 1.9 went in the guage would stay in exactly the same place until the motor was pushed hard when it would climb rapidly and seemingly burp a bit of coolant out of the rad (no header)
After a few times doing this the coolant would be getting low and the overheating would get progressively worse, I never let it get into the red.
Is this the 1.6 block / 1.9 head engine you mentioned in another thread ?
Same head but with a 1.9 block and the 1.9 injectors
I'll set the timing back down to 1.00 and see how it goes....
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no, not pegged the gauge as in maxxed out.
As in the needle sat at halfway and didn't budge, maybe creep up 1mm on a long hard climb
As soon as the 1.9 went in the guage would stay in exactly the same place until the motor was pushed hard when it would climb rapidly and seemingly burp a bit of coolant out of the rad (no header)
After a few times doing this the coolant would be getting low and the overheating would get progressively worse, I never let it get into the red.
Is this the 1.6 block / 1.9 head engine you mentioned in another thread ?
Same head but with a 1.9 block and the 1.9 injectors
I'll set the timing back down to 1.00 and see how it goes....
Reg
If you're set to 1.2 with 155's then going to 135's could EDIT effectively put you up to the equivalent of 1.3 to 1.4 if you were staying with the 155's:o
Run the engine and with the pump bolts loose swing pump to get the 'tuned position. Repeat at fast idle incase there is some difference, which there may be if your pump is not advancing correctly.
Back to your burping problem:
Can you be sure that you don't have a slight head gasket leak, that only shows up under reasonable loading?
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135's run a lower timing spec than 155's.
Seems he could run lower timing with 135bar, not higher ?
But its no big deal - unless he needs to go that route.
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135's run a lower timing spec than 155's.
Seems he could run lower timing with 135bar, not higher ?
But its no big deal - unless he needs to go that route.
I totally agree Mr Baron...
My point was intended to say that with the already high setting for 155's, it would effectively be like running with further advancement, like 1.3 to 1.4 [for the 155's], if 135's swapped in.
I will edit my previous post so that it reads correctly ;D