A question about Engine Temperatures

[Tinster]

Just about 1 year ago Wendy gave me the Crypt
Car for Christmas. I noticed the temperature gauge
did not seem to function. The P.O. informed us
that was normal because Triumph engines usually
run very cold. Then the radiator immediately blew up.

Thus began the Crypt Car saga. Water temperature.

Crypty started this morning and I took him out
of the neighborhood. Yeah, I know- a truly foolhardy
thing to do but only 2 miles from home in case I had
to walk back)LOL

The new temp gauge usually sits at 180* when I am
on the street moving. I parked in the garage but
did not turn off the engine. Temp. zoomed up to
near 195*

So I got out my infrared pistol and shot the head
area around the water sensor unit=188*

Area beside the spark plugs=195*

Carbs=165*

Intake manifold= 170*

I ask this ?? and post the #temps because
the Crypt Car runs on and on after I turn off the
key. The MG mechanic said that is because my engine
is running too hot.

What are normal operating temperatures for a regular
TR6 1969? If mine are too high, how do I bring them down to normal ranges?

PS: The PO completely removed the heater system all
heater related pipes. Both pipes on the ends of my
intake manifold are capped off.

thanks,

d

 

[martx-5]

It's normal for he temperature to rise when the car is sitting there idling. There is less air going through the radiator because there is no forward motion, and the fan is spinning slower because the car is at idle. This lack of air volume through the radiator causes the temp to increase.

This is one of the reasons that I'm in favor of electric fans. They only work when neccessary, and when they do go on, they are working at peak efficiency. It just seems to me that engine driven fans are moving the most amount of air when you least need it, and the least amount of air when you most need it. /ubbthreads/images/graemlins/hammer.gif

BTW 195 deg isn't too hot. As far as the engine running on, that could an entirely different problem. Too much heat can make the problem worse, but I don't think you are at that point. How high is the idle set?? Is the heat range of your plugs correct?? Is the timing correct??

Edit: I'm not all that familiar with the effect of not having coolant run through the intake manifold, but those Triumph engineers put it there for a reason. Perhaps someone with experience can shed some light on what's going on with that. I would be inclined to put that back in operation.

 

[RomanH]

The reason for the water running through the intake manifold is to aid in vaporizing the fuel before it is introduced to the cylinder. The manifold needs to get up to temperature quickly to do this otherwise the fuel remains a liquid and does not mix properly and then the engine runs poorly.

 

[shorn]

Not a cure, but a way to eliminate the run on problem. Put the car in second gear, right foot on the brake, left foot depressing the clutch. Shut off the key and release the clutch, keeping your right foot solidly on the brake. The engine will immediately stop.

 

[jerrybny]

Dale your temp readings sound close to what my 73 TR6 readings are. The running on is usually related to the timing. Hope this helps. Happy Holidays

 

[Alan_Myers]

Hi Dale,

Nothing to worry about with those temps. They are great. I wouldn't try to decrease them at all or you might start having problems with sludge in the oil, etc. (I agree with Art's points about an electric fan being preferable, though.)

I dunno about the preheated manifold either (it should be easy to reconnect to see if it helps, though).

There are a number of other possible reasons for run-on like you describe:

That's often refered to as "dieseling" because it's the way a diesel engine operates: no spark plugs, just a glow plug that causes the fuel/air mixture to combust when it's compressed. In a non-diesel engine it happens when something is glowing hot in one or more of the cylinders, causing the engine to keep running although the ignition has been turned off. The glowing can be caused by a sharp edge that heats up, or by some carbon deposits, or by an incorrect spark plug. It can even be a head gasket that's got sharp edges slightly protruding into the combustion chamber, heating up and glowing to cause the engine to keep running.

Other things can contribute to it, such as ignition advance/retard settings. Increased compression (by milling the head) can be another factor, especially if combined with poor quality/low octane fuel.

Some cars are simply so prone to dieseling that an anti-runon valve is installed on the intake manifold. This opens up when the ignition is turned off, allowing atmosphere into the manifold to quickly dilute the remaining fuel/air mixture to the point the engine stops immediately. It sounds like the previous owner of your car removed a lot of things related to emission controls, perhaps it had an anti-runon valve originally?

Run-on isn't all that bad. Some folks just "dump the clutch" with the car in gear, to make the engine stop running on. A little crude, but it will work and probably won't do any harm.

What you need to watch out for is pre-ignition or detonation. These are two other things that can happen if the engine is running with incorrect mixture, too advanced timing, etc., and in some cases they can do serious damage. Usually these are associated with higher engine temps, though. You can often hear them, too, as as a "pinging". The engine might backfire, too, at times. Check the spark plugs are a nice even grey color and not pitted, burned or covered with metallic specks. You can have a shop run an exhaust gas test, too, to find out if the car has any mixture problems.

If it's carbon in the cylinders, the problem could clear up after the car is driven some more. Be sure to use good quality premium gasoline, perhaps one with a lot of detergent additives (Chevron, Shell) would help.

Double check that the spark plugs are correct for the engine and properly gapped. Check the timing/advance/retard, maybe just back off advance by a couple degrees to see if that solves it. You also might have the advance curve of the distributor checked at a local shop (most dizzys' curves can be modified and adjusted by changing weights and springs inside).

Some of the internal engine causes of run-on are more difficult to deal with, really mean the head has to come off to identify the culprit. So, I'd try to eliminate tje easy stuff as a possible cause first and just keep an ear out for more serious issues like pre-ignition and detonation.

It sounds like you are making a lot of progress, though!

Happy holidays!
/ubbthreads/images/graemlins/cheers.gif

 

[Guest]

[ QUOTE ]

PS: The PO completely removed the heater system all
heater related pipes. Both pipes on the ends of my
intake manifold are capped off.

thanks,

d

[/ QUOTE ]

You devil, you never told us that the manifold coolant pipes were bypassed. This is the entire reason the Crypt car doesn't run!

Well, one of the reasons anyway. You should have these hooked up, helps pre-heat the fuel. You can do this without a heater, just use your imagination.

 

[Bob_Muzio]

I believe I read that to achieve the most accurate temp reading with the infra red thermometer is to shoot a black surface. On my TR4 I used the upper radiator hose or the radiator where said hose attaches to get a temp reading. Remember the car's gauges, be it the water temp, oil pressure or fuel gauge are known for their inaccuracies.
Bob

 

[YankeeTR]

Dale,

Run-on is often caused by too high of an idle speed...in the case of my old TR3 it was caused by a vacuum leak. Try turning the idle speed down a bit and that may help.

The heated intake is simply used to warm the intake manifold so the fuel is better vaporized during cold weather...not needed in PR. You actually want the intake as cold as possible during warm weather to combat fuel vapor lock and other warm weather problems.

 

[fad64b]

My experience with an engine continuing to run after the ignition is turned off. Has always been the fuel, the octane is too low for the compression of the engine my understanding is that the higher the octane level the less likely the fuel will explode under pressure with out ignition.. Thus the higher the compression ratio of the engine the higher the octane fuel needed

 

[70herald]

[ QUOTE ]
The P.O. informed us
that was normal because Triumph engines usually
run very cold.

[/ QUOTE ]

Where at the North Pole??? Triumph engines only run cold if you take out the thermostat. With the thermostat in they run at the right temperature (when everything is working properly) or overheat. The numbers you have sound reasonable.

[ QUOTE ]

PS: The PO completely removed the heater system all
heater related pipes. Both pipes on the ends of my
intake manifold are capped off.


[/ QUOTE ]

So are mine, actually, they rusted off. Your DPO probably removed the heater because these pipes rusted out also. The pipes are mild steel and rust.

This only confirms that both of our DPOs were either evil brothers or went to the same school of bad auto care.

Quite a while ago, I asked John Kipping about this and he said that the only downside is that the engine will need the choke somewhat longer. Both of us are in basically warm climates. If you lived somwhere cold, this could cause more problems.

Taking a good look at my modern Toyota, I see that it also has a "heating" pipe running through the intake manifold to heat it up. As soon as the engine is warm, it shuts off the hot water flow. This make sense. In order to get more power out of the engine we want denser air. Cold air is denser. So while the engine is cold, we want to help heat it as quickly as possible (for better vaporization of the gas) but once the engine is hot, vaporization is no longer a problem, so we really don't need any more heating of the intake.
Yisrael

 

[swift6]

Its not just for heating purposes but also for cooling purposes.

Yes as the coolant heats up it helps heat the manifold to aid the engine in warming up. But just as its called 'coolant' for a reason, once the engine is warmed up it helps cool the manifold to a stabilized temperature. Even though the intake manifold is aluminum and sheds heat pretty well, it does sit just above the exhaust manifold/header. The coolant running through the manifold does help wick away heat from the intake area. Thus also helping to keep the air charge cooler and therefore denser. If you remove the added benefit of coolant running through the manifold, and rely only on the inherent nature of the aluminum to wick away the heat, especially if sitting over headers, then you'll end up getting a hotter and therefore less dense air charge.

As hard as the above might be to understand. Spend enough time thinking about it and it too will make sense. You are better off having the coolant pipe through the manifold hooked up and operating than to leave it out of the overall cooling system.

If you are looking for a way to cool the air coming into the engine, this is not it. You are far better off directing air from directly in front of the radiator via an airbox or using vents like TR6Bill has.

Dale's wonerful PO removed the entire heater unit as part of his 'restoration'. So Dale's car is probably also missing the return pipe that runs under the manifold and enters the back of the waterpump housing via that huge pipe threaded fastner.

 

[Tinster]

Thanks Yisrael! Much appreciated.

When the radiator blew up the 2nd day we
owned the Crypt Car, I noticed there was
no thermostat installed. So I put in a new
thermostat, temp sender and radiator and
eventually a new temperature gauge.

thanks

Dale in Bayamon, Puerto Rico

 

[70herald]

[ QUOTE ]
Its not just for heating purposes but also for cooling purposes.

Yes as the coolant heats up it helps heat the manifold to aid the engine in warming up. But just as its called 'coolant' for a reason,

[/ QUOTE ]

Shawn,
As a mechanical engineer, I am rather well aware of how the cooling system works.
In this case however you would have to get some very strange conditions indeed for the water pipe to cool the intake. Just think about it, the water is ~200F so the intake would have to get significantly warmer before the water pipe will start cooling. Having driven my car without the heater pipe attached, I assure you it will not reach 200F. You can hold your hand on it with no problem. The heat radiated from the exhaust will heat it to some extent, however air flow through the engine compartment, and also the air flow within the manifold will cool it far more. The real problem begins when you park and the latent heat boils off all the gas in the carbs, and causes gas bubles in the fuel line (vapor lock). Then you have a problem next time the car is started.
Yisrael

 

[angelfj1]

My 250 used to run-on. I finally adjusted the timing a bit (retarded) and I solved the problem with no reduction in performance.

 

[Tinster]

What does retarted timing mean?

My 250 has only 2 timing marks on the pulley.
A heavy line and then a shorter line.

My timing is set dead on the heavy line.

I'm thinking I will put some high test gasoline
in the tank before I start messing with anything else.

As set up now, finally, the Crypt Car will start most days.

thanks,

d

 

[swift6]

[ QUOTE ]
[ QUOTE ]
Its not just for heating purposes but also for cooling purposes.

Yes as the coolant heats up it helps heat the manifold to aid the engine in warming up. But just as its called 'coolant' for a reason,

[/ QUOTE ]

Shawn,
As a mechanical engineer, I am rather well aware of how the cooling system works.
In this case however you would have to get some very strange conditions indeed for the water pipe to cool the intake. Just think about it, the water is ~200F so the intake would have to get significantly warmer before the water pipe will start cooling. Having driven my car without the heater pipe attached, I assure you it will not reach 200F. You can hold your hand on it with no problem. The heat radiated from the exhaust will heat it to some extent, however air flow through the engine compartment, and also the air flow within the manifold will cool it far more. The real problem begins when you park and the latent heat boils off all the gas in the carbs, and causes gas bubles in the fuel line (vapor lock). Then you have a problem next time the car is started.
Yisrael

[/ QUOTE ]

Yisrael,
My responses are not aimed solely at you but are more explanatory for the benefit of those reading along who might be looking for a bit of education on the subject as well as understanding the topic area. So forgive me if I cover things you 'understand'.

I can't speak for sure on your Herald or Starlet, and I'm no mechanical engineer, but on the TR6 the intake coolant pipe is part of the bypass system. It sees coolant from the head only until the thermostat opens. Once at operating temperature it sees the coolant after it flows through the radiator. Unless, the heater is on and then it sees it after the heater. But is still mixed with cooled fluid from the radiator before passing through the intake manifold.

So it is set up to have cooler fluid running through it when it is hot outside and warmer fluid when it is cool enough for the driver to turn on the heating system. In warm weather, heater off/thermostat open, you would have to have severe overheating issues for the coolant running through the intake manifold to be at 200 degrees as it would have to be that hot when it left the radiator.

Now I know 'cooling' might be overstating it a bit as to what the coolant does when piped through the manifold. It might be more appropriate to say that it stabilizes/equalizes the temperature across the manifold, eliminating hot spots, so that cylinders 1-6 get approximately the same density of air. If the carbs are right and are metering the same amounts of fuel then you stand a better chance of equal air/fuel charges in all six cylinders. Not counting the inherent distribution inefficiencies of the stock intake manifold. The result should be a more stable and smoother running engine.

I have seen TR6's, with the manifold coolant bypassed, that on warm days would have intermittent running issues where the idles would hunt up and down and mild rough running. Yes it was much more exaggerated when the car was not moving and not really noticeable while going down the road as then the air moving through the engine bay and increased air moving through the carbs and intake helped smooth it out.

When the coolant was rerouted through the intake manifold, as it was designed to, these issues would disappear. It does not make any discernible difference on whether or not the car vapor locks as it does not cool the carb float bowls, but TR6's in general don't often suffer from vapor lock when all is well on the car. Also, if memory serves correctly and Dale hasn't fitted an entirely new exhaust system yet, he does have headers that would lead to higher under hood temps.

Bottom line is that you can run around with the intake coolant pipe eliminated from the system. The difference with it in use is usually slight but on the smoother side of operation. Its there to aid drive-ability but eliminating it won't improve performance to any measurable degree either. Not speaking of theory, but of experience. As with most things in life. YMMV

Shawn

 

[swift6]

[ QUOTE ]
What does retarted timing mean?

My 250 has only 2 timing marks on the pulley.
A heavy line and then a shorter line.

My timing is set dead on the heavy line.

I'm thinking I will put some high test gasoline
in the tank before I start messing with anything else.

As set up now, finally, the Crypt Car will start most days.

thanks,

d

[/ QUOTE ]

Dale, Advance and Retard can be confusing at times to understand. It has to do with timing the spark for optimal combustion efficiency as the piston approaches top dead center. As the engine speeds up, spark needs to occur earlier (advancing the spark timing) so that optimal combustion can match the increased piston speed. Retarding the spark timing will allow it to occur later.

Here is a tutorial on the basics of ignition systems.

High test might not be the answer unless your compression ratio has been increased at some point. It definitely won't hurt and you might be able to convince Cryptie that it's a treat for current and future good behavior. /ubbthreads/images/graemlins/jester.gif

While standing on the distributor side of the engine and looking down at the pulley, when the 'heavy' line is at the pointer, is the short line closer to you or farther away from you?

 

[Dave Russell]

[ QUOTE ]
[ QUOTE ]
Its not just for heating purposes but also for cooling purposes.

Yes as the coolant heats up it helps heat the manifold to aid the engine in warming up. But just as its called 'coolant' for a reason,

[/ QUOTE ]

Shawn,
As a mechanical engineer, I am rather well aware of how the cooling system works.
In this case however you would have to get some very strange conditions indeed for the water pipe to cool the intake. Just think about it, the water is ~200F so the intake would have to get significantly warmer before the water pipe will start cooling. Having driven my car without the heater pipe attached, I assure you it will not reach 200F. You can hold your hand on it with no problem. The heat radiated from the exhaust will heat it to some extent, however air flow through the engine compartment, and also the air flow within the manifold will cool it far more.
Yisrael

[/ QUOTE ]
Hi Guys,
"Air flow within the manifold"
Just to further illustrate this air flow. I once instrumented an engine by putting thermocouples in the intake ports, near the intake valves. This was a turbo charged engine with supplemental water injection to help control detonation. To illustrate: see attached graph - The point of interest to this discussion is the area of the graph marked "Cooling Due To Airflow & Fuel Evaporation".

The point is that the intake charge temperature was dropped from 400 degrees plus to 250 degrees, just by intake air flow & fuel evaporation. 100 or more CFM of wet (fuel laden) air flow through a port is capable of removing a "lot" of heat.

It is likely that at low air flows the water jacket in the intake manifold would serve it's very useful purpose. As throttle settings were increased, the much greater air flow & evaporative cooling by the fuel would overcome the manifold water jacket heat by a large margin. Many engines rely on exhaust gas to heat the intake manifold & work in a similar way. The "hot spot" is too small to cause mixture heating at the higher RPM air & fuel flow levels, which is exactly what is needed.

Note that even at zero boost, the intake charge temperature is dropped about 70 degrees just by air flow & fuel evaporation.

On this particular installation, additional water injection charge cooling was used to drop the intake temperature a further 100 plus degrees.
D

 

[Tinster]

Shawn: Standing at the distributor, the
short line on the pulley wheel is AWAY from me.

d