The Heat Of It........

[Guest Sean Timney]

Hi guys,

 

Started my engine for the first time in 7 months since coming out of the Sierra......was a bugger, but got there eventually......I have some problems though....

 

Firstly, the engine (following some distributor moving!), seems to run, although still sounds a bit lumpy....but worse than that, when the temp needle hits the middle of the 'N' on the NORM letters on the gauge, the thermostat seems to open and it drops to the top of the 'O'...after rising again, the oil light comes on (tried pumping the accelerator hoping it would cure the low pressure with no luck.....turned off engine and waited for it to cool........started up again when needle in the 'M', with no oil light present again until it hits the 'N' (sorry for the simpleton description, but i'm trying to be as clear as possible on this).....once the light came on, i turned off the engine once more.......what's causing this guys?.......I have the following:

 

2.0 Ltr carb (man choke)

New Temp and Oil senders fitted

New Thermostat (yes i think its in the right way)

New water pump

Fresh oil

New plugs

New HT Leads

New Filter (oil)

 

One thing I also noticed was that the top of the radiator (after the temp had dropped slightly) was red hot (as i would expect), but the bottom was very cool....I guess I could have an air lock in the system, but would this cause the oil light to come on??....I would'nt have thought so.....with only being early on in my build, i don't have a heater, so i've plumbed in some copper pipe which runs from the pump over the top of the rocker cover to the inlet manifold to complete the cooling system

 

Also, i'm running unleaded and i know its a leaded head.......getting hold of 4 star (or lead replacement), is a bugger where i live. I would think that this would only cause excessive heat on the valve seats/guides.....

 

Is there something more sinister going on here?

Should the engine running temp be up in the 'N'?...this seems a bit close to the red for my liking!!

 

Can anybody shed light on this problem?.....I know the timing could still be out (got somebody coming to look at it on Friday)

 

Sorry for the length of this mail!!

 

Thanks,

 

Sean.

[Guest Ant]

OK here's my thoughts.

 

1) Don't run a leaded head on unleaded unless it has had the seats ground or whatever they do. The timing also needs to change which will explain your rough running. Whilst your engine will start on unleaded, it won't take long for the valves to sieze - a catrastophic problem depending on how it happens.

 

2) I can't see what the coolant has to do with the oil pressure. This is more likely to be a wiring or earth related problem.

 

3) Going up to a high temp, and then falling when the thermostat opens is all quite normal. Once the thermostat is open it should warm up again back to about the same point as before on the gauge, and then the fan will kick in. I'm assuming you have an electric fan with thermostat control. If not then fit one - you'll only regret it later if you don't.

 

4) Have you fitted an expansion tank in the cooling circuit? Any air locks should work themselves round to the top of the radiator, and be the first thing out when it warms up. Ideally this is connected so that the air bubbles to the top of the expansion bottle, and coolant is sucked back when it cools down again.

 

5) Have you flushed the cooling system through - is everything free flowing?

 

6) Running with the gauge just below the red is fine. If it gets into the red then you've got trouble. I used to panic loads when I first got my engine running, but I'm used to it now.

 

Hope that helps.

 

Ant

[Guest Sean Timney]

Thanks for that Ant, much appreciated.....i don't have a header tank and I have an electric fan but i've had to hot wire it for the time being as i've got no thermo switch. I'm really early in my build, just wanted to start her up ASAP to make sure everything was OK.....or not as the case may be.

 

Sean.

[Guest Simon cooper]

Hi guys,

Sorry Ant, I hate doing this but you are wrong about the unleaded, the rough running and valve siezure.

If you were to use unleaded in a leaded head for 5000 miles and you inspected your valve seats, you would see very little wear. Valve siezure is practicaly unheard of and not caused by unleaded fuel unless you are racing the thing constantly.

The rough running, if due to the timing would have to be out a damn sight more than 4 degrees which is needed to retard for unleaded fuel. Timing generaly does not cause rough running but a flat engine, ie poor pick up or pinking. The temp change due to running unleaded is not enough to increase the water temp to a seriously high level, nor is over advance on the timing, definately not running up in the garage.

Put up with the rough running for the minute, that is easier to sort out. Your problem to address at the moment is oil pressure. A couple of things come to mind, crap in the sump blocking the strainer, too thinner oil being used, worn ends or weak oil pump.

The cooling time of the engine would have to be a few hours for there to be any significant change in viscousity of the oil.

Firstly, I would remove the sump, check for the old black death, strip and inspect your oil pump and check the oil pump drive into the bottom of the disi.

Wiring and earths are not generaly affected by temp so I think you can bin that idea.

Sorry again Ant, there is a lot of nonsense kicking around about unleaded, has been for years. LRP is just crap with no BS number and gives you sod all protection once you are on open roads at speed. Personally, if you have a leaded head, retard the ignition by 4 degrees and use unleaded. While pinto heads are still plentiful, get hold of one for a spare to use in years to come. The mileage that we are doing in the summer months, it will take about 5 years for you to feel the effects. Just checking your valve clearances every 4 to5 months will indicate the wear to your seats. they close up as the seat degrades.

Simon

[Guest Fred2b]

I had a similar problem with my everyday car a VW Golf about 6 months ago.

The water temp guage has never worked from day one of owning this car.There was an airlock in the system or the thermostat was faulty, I'm not sure which, causing the top radiator hose to bulge out with hot air pressure. This caused the seal around the water pump to go thereby releasing the pressure. However the engine got so hot and so did the oil causing the light and warning buzzer to come on.

A new thermostat and carefull bleading sorted it.

Fred

[Guest Sean Timney]

Thanks guys.....i'm not so worried now!!

 

Sean