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boogie

Radiator cap and high running temperature

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This has been covered before, but the direct question not quite answered hence me asking. Apologies if I've missed it from other posts, or indeed missed the other posts completely, I did try a search first of all.

A friend gave me a hand with my timing, setting it up by lining the dizzy up with the position of the rotor arm, but we couldn't get smooth acceleration and it seemed like there was a misfire on a cylinder. Since then I've taken the gamble that the tdc mark is lined up properly after my engine rebuild (my dad was a stickler for doing things right, so I'd imagine he'd do this as well) and used my timing strobe to set at about 14btdc. She seems to be ticking over nicely and runs a bit smoother, although still some fettling required. Tick-over is about 800 rpm.

I took the car for its first run but returned quickly as the temperature gauge was approaching the red line. This is a standard engine with the standard fan. The heaters are blowing warm and the radiator was warm. The car seemed to get to mid-temperature on the gauge within minutes of starting and I was only out for about 10 minutes before I panicked and went home. I've since noticed the radiator cap is marked with 7lbs not 13lbs.

Would the rad cap account for such a rapid rise in engine temperature, or is there a suggestion I might still off with the timing as well?

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The radiator cap will not influence the heat-up rate. The higher pressure rated cap will allow for a higher water temperature before boiling occurs.

my CP- PI is set at 11degrees btdc.

But I don’t think a couple of degrees off will cause quick overheating.

Waldi

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Thanks Waldi. Just as I think I'm making progress I keep getting these problems. I'll get a new rad cap tomorrow then run through the list of possible solutions/areas to check :-(

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12 minutes ago, Waldi said:

The radiator cap will not influence the heat-up rate. The higher pressure rated cap will allow for a higher water temperature before boiling occurs.

my CP- PI is set at 11degrees btdc.

But I don’t think a couple of degrees off will cause quick overheating.

Waldi

I agree with Waldi's comments.

Has the engine been out or the coolant been drained recently? Such a rapid temp rise could be due to an airlock, happens all too easily if the cooling system has been drained and refilled.

To get rid of an airlock, raise the front of the car as high as possible. While filling the rad, repeatedly squeeze the radiator hoses to help any air to find its way out.

Nigel

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Just now, Nigel Triumph said:

Has the engine been out or the coolant been drained recently?

Thanks Nigel, and yes the engine has been out of the car in the no-too-distant. This is the first time the car's been back on the road since 1985 and my dad rebuilt the engine about 8 years ago. The car's now all back together again and I thought air-free. I think I'll get the nose raised and see if there's any more in there.

The temperature did seem to go down (I presume when the thermostat opened) but I didn't like how quick it warmed up in the first place

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My rad cap is 7lbs too and didn’t have any issues in 35 deg c Spanish summer last year.  I concur with Nigel and Waldi, your problem lies elsewhere. 

 

Cheers

 

dave 

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Looks like the thermostat may not be opening. If the engine's been laid up for a long time I'd remove it, check the opening temperature stamped on it is correct , and test it's opening correctly by boiling it in a pot  of water.

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40 minutes ago, Mike C said:

Looks like the thermostat may not be opening. If the engine's been laid up for a long time I'd remove it, check the opening temperature stamped on it is correct , and test it's opening correctly by boiling it in a pot  of water.

+ 1 + newly rebuilt engines eat up quite a bit at the beginning and it goes back to normal after 1 hour usage 

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If the voltage stabiliser is faulty reading 12v instead of 10v how will it affect the reading of the temp sensor/gauge?  Will the readings be high or low on the gauge?

If the engine has been rebuilt recently wouldn't the water jacket heat up a bit quicker than a run in engine?

John

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You can check the water temperature gauge reading with an infra red gun. They are not expensive.

Depending on where you take the reading, you may have a bit lower readings, but it will give a good indication. Avoid reflective surfaces like SS or polished aluminium, as they are fooling the reading.

I don’t think friction of a new built engine should give much higher water temperatures. The cooling capacity is pretty oversized. If the heat from friction would create boiling water, the bearings or pistons would have probably gone broke before that.

Some additional suggestions to the above good points:

Have you checked the cylinder head bolt-torque? 

Do start up with the radiator cap off, so you can see the water-flow and add water if needed.

If in doubt about the thermostat (if all the above is checked), remove it temporarily. Have nee gaskets at hand. You can then also check the proper functioning of it in a pan with hot water. Check when it starts to open and when it is fully open. Should open about 12 mm, there was a post around this last week.

Good luck, you will get there.

Waldi

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Thanks everyone. I'm heading over to Warrington to pick up some parts in readiness to have a look at a few of your suggestions.

I've got an infra-red thermometer somewhere. It was one of those purchases that seemed good to have but I never actually used. Maybe it'll come in useful now.

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Have you replaced your temp sender, mine was reading into the red. Using thermal imaging, digital thermometer and an Infrared thermometer I concluded the engine was running at normal temp. Rigged up old sender in boiling water attached to car via earth and guage feed, temp guage went below half way. 

Worth a check. 

Mark

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7 hours ago, Mark69 said:

Have you replaced your temp sender, mine was reading into the red.

I've been to pick up a few spares and was given a second-hand working temperature gauge to try and also bought a new sender. The sender should've been replaced as part of the rebuild, but after finding a few things that should have been done but weren't I'm not so sure.

I've got quite a few jobs to get on to, just need the time to do it now amongst my day job - I know what I'd prefer to be doing ;-)

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No real update on the symptoms I've been experiencing, or from me saying I've tried any of your suggestions yet, but I have had another look under the bonnet tonight and noticed a few things.

The temperature sender does seem to be a new one so I'm happy to take back my questioning of my mechanic's work in this respect

The radiator needed topping-up so I used the now full overflow bottle and noticed the water was very rusty looking (potentially a little oily, but no mayonaisse)

The heater return pipe where it connects to the water pump seems as though it has a slight leak - this was leaking a lot more until recently when it was tightened a bit more - and there seems to be an oily-residue around the connection

There is what appears to be an oilly residue on the engine block just below the distributor body and above the oil filter

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If the coolant is “rusty”, you better flush the system until clean with a water hose and then replace it. I had the same after a rebuild, the scale that was left from cleaning the block waterside with phosphoric acid became airborne in the new coolant when I warmed up the engine the first time.

I suspect it contributed to my (similar) cooling issues at the first start.

Re. The oily residue: whipe clean and check the next time you are starting the engine with a torch; the black engine paint is a perfect camouflage for oil leaks (yes, how do I know). My leakage came from the rear end of the rocker cover.

Waldi

 

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You could try running without the thermostat for a short while. If the engine stays cold the problem is the thermostat or an air lock.

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I had some issues and this is what I went through:

- Check thermostat in a pan of water and see it opens

- Check temp sender - I had one (new) that was wrong.  I only found this by using a heat gun.  This is a great purchase and cheap off ebay.

- A good flush!

- Burp the coolant.  I jacked up front and ran engine with radiator cap off.  When hot it literally went 'burp'.  To avoid mess, I cut a windscreen wash water bottle (which you see outside garages) in half,  wrapped tape around outlet and then that goes into radiator.  All this does is make a overspill chamber for coolant to run into when it gets hot.

If non of above, maybe something more serious. 

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Hi Mark

Half a wheel height is fine.  Concept is that air rises and therefore by jacking up, the air moves to the front of the car and then exits from the radiator cap hole - also squeezing top hose gently helps circulation.  In the old days, I believe mechanics just went and found a hill and ran the car with cap off.  

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I fill from the heater hose (disconnected from the heater valve) with the hose held high.  Filling from this point which is higher than anything else in the engine bay results in coolant over spilling from the rad (meaning system full). Reconnect hose, start up car with cap off to give opportunity to burp .... then job done. 

 

Cheers

 

dave

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Well, a little bit of progress then not.

I drained the coolant - I say coolant in the loosest sense of the word, as it was pretty much just rusty water. Fitted a new thermostat and checked the water pump was still functional. I've left the temperature sender and gauge for now to see how things pan out.

Afterabout 10 minutes on tick-over the temperature seemed ok and I was getting warm air through the vents. Then disaster. My car decided, whilst I was staring in the engine bay and darting around to check on temperature, she was going to mark her territory. Oil all over the floor on the passenger side about level with the firewall.

I've given up for now and will look at the oil issue in a few weeks when I'm back from working away (another two steps back!!!)

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It can be something simple like a rocker cover gasket, which occurred in my case after an engine rebuild; I did not want to overtighten the 3 nuts of the cover.

Whipe the engine clean and look with a bright torch next time you have a look.

Waldi

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44 minutes ago, Waldi said:

Whipe the engine clean and look with a bright torch next time you have a look.

Thanks Waldi. I decided not to get too downhearted and have just been back in the garage to do as you suggest. There's no huge puddle under the car so that's good. The oil level is still above minimum and I've wiped over all the surfaces. There's no oil at a higher level and the first oil I can find is around the distributor pedestal. There's then oil all along the lip of the sump to block, so I've cleaned that completely now. There's no oil on the driver side anywhere (rhd car). The main oil residue is arond the sump plug and the drain plug of the gearbox. My oil is rusty again, so I need to flush through again - I suspect all the crud's in the heater and/or engine

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21 minutes ago, boogie said:

My oil is rusty again, so I need to flush through again - I suspect all the crud's in the heater and/or engine

Boogie do you mean the water is rusty again?

Paul

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41 minutes ago, Paul J said:

do you mean the water is rusty again?

Yes, I didn't manage to clear through the engine or heater, just the radiator

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