overheating problem after serp engine cam change - help!

[IainGriff]

just fitted stealth cam to my 500 serp, refilled cooling system, started up and after the initial clatter of cam followers the engine sounds sweet. However the indicated temperature shot up and kept on climbing past 90C so shut down. tried numerous procedures described on the forum including bleeding the rad, rigging up a pipe and funnel to fit in to the header tank/swirl tank and much squeezing of hoses to expel air. All to no avail, the temperature still shoots up above 90 in just a minute of starting.
Am I missing something? the bottom hose from the water pump gets hot, both heater rail pipes got hot but the radiator top hose stays cold as does the header tank and hose to the thermostat .
I did wonder if it is possible to fit the valley gasket round the wrong way and thereby block off a waterway, if not it would seem that I have an airlock somewhere.
Any one else had this problem following a complete drain of the cooling system, advise would be much appreciated.

[Quinny]

Try back filling.... Stick a pipe in the header tank and feed it down the neck to the water pump... Pour water in until it starts coming out of the pipe into the main header....

This method has alway worked for me

[IainGriff]

I take it you had a similar problem with a serpentine engine or is it just me?
I thought that maybe my makeshift pipe and funnel arrangement having a head of water 18" above the header combined with squeezing the flexible hoses would have forced out the air. However I'll give your solution a go, can you confirm you did mean to say into the thermostat housing rather than the water pump. Unfortunately I'm away now until tuesday week, will get wify to source some suitable piping and have a go when I return.
Thanks Quinny

[Quinny]

Yes... I did mean the thermostat housing...... Mine was a pre serp, but this method never failed for me.... Got to be worth a try?...

[TVR Beaver]

Don't think you can get them wrong ?...



Sounds like your stat is stuck?.... did you blead the LHS head with the small pipe and bolt in the tube?

[ronspeedsix]

What's the red stuff with the camfollowers ?

[TVR Beaver]

ronspeedsix said:

What's the red stuff with the camfollowers ?

Ha... That’s very important.. if you don’t use that, eventually they will start ticking when the engine is warm.. intermittently at first, but then all the time as the engine beds in…

No.. only joking.. was reading your post about your ticking noise!.. sound like you have a bit of a blockage in a lifter to me on that or one that’s bleeding down a bit …

It just lubrication for the engine re-build.. You can’t quite see the cam but that’s covered in white cam grease also… so you can turn them over whilst on the stand being re-build without them marking one another and potential picking up

[Colin RedGriff]

IainGriff said:

All to no avail, the temperature still shoots up above 90 in just a minute of starting.

That is very fast.does the engine actually get hot in a minute?

Might be an electrical issue, the sender connection might have been disturbed?

Have you got Rovergauge to see if the ecu sensor agrees?

[TVR Beaver]

Does he actualy mean 1 min??.. if he does then yes.. its way too fast to be realistic..

another thought.. have you put the belt back on correctly... and your spinning the pump the right way?

[Colin RedGriff]

Good call on the belt too

[Pete Mac]

IainGriff said:

.... However the indicated temperature shot up and kept on climbing past 90C so shut down. tried numerous procedures described on the forum including bleeding the rad, rigging up a pipe and funnel to fit in to the header tank/swirl tank and much squeezing of hoses to expel air. All to no avail, the temperature still shoots up above 90 in just a minute of starting.
Am I missing something? the bottom hose from the water pump gets hot, both heater rail pipes got hot but the radiator top hose stays cold as does the header tank and hose to the thermostat .
I did wonder if it is possible to fit the valley gasket round the wrong way and thereby block off a waterway, if not it would seem that I have an airlock somewhere.
Any one else had this problem following a complete drain of the cooling system, advise would be much appreciated.

Just trying to think it through in my head as I sit at my desk. Far more interesting than work....

Even if you had a sticky thermostat, it would take longer than a minute for the temperature to go above 90c. When you start the engine up the thermostat will stay closed anyway for at least 5 minutes or more until the water reaches running temperature.

I have the same set up as you, funnel and long tube, (subject of a separate thread) but I do manage to bleed the system but it takes quite a time, squeezing hoses etc. I fill the funnel then leave the motor running until the engine warms up, when the thermostat opens the level in the funnel drops - does that happen with you? or don't you have a chance to check before the temperature rises to 90c?

Just as a sense check, where is your temperature sender, at the bottom of the swirl pot or in the radiator? because you could do a 'sense' check and put your hand on the sensor when the temp gauge shows 90c and just check to see if the sender is hot or not - it sounds supiciously like the sensor could be faulty.

My only suspicion is that this is happening straight after fairly major work on the cam and valley gasket etc. - a bit coincidental. On that, someone else will have to answer if a waterway may be blocked, however that still wouldn't account for your temperature shooting up because that would be back at the sender.

Hope that's not too much rambling. Long and short of it is start by swapping out the sender and then go from there. Pete

[TVR Beaver]

Pete Mac said:

Just as a sense check, where is your temperature sender, at the bottom of the swirl pot or in the radiator?

Thats the fan switch.. the temp sender is in the manifould

[IainGriff]

Looks to me from the photo that you can't really get the valley gasket round the wrong way.

A good call TVR Beaver, I haven't bled from the small short pipe with the bolt in the end of it, I assume there could be an air lock.
I'll go for the stat next. I'm away for the next week so will give it a go when i return home.
Thanks all for your responses, I will post again hopefully with good news.

[Peter66]

Perhaps you hit the distributor during the installation. If the timing is out it can get hot quickly. An indication is very hot exhausts in no time.

Peter

[Pete Mac]

TVR Beaver said:

Thats the fan switch.. the temp sender is in the manifould

Good point, my mistake. So this points even more to either a problem with the sensor or some mysterious airlock in the manifold.

I don't think the timing being out will heat the engine to 90C in a minute. If it's that far out then you may have a problem starting the engine.

The problem is you don't want those high temperatures for long so shutting off the engine after a minute is the right thing to do as the alternative could be catastrophic.

A relatively cheap check would be to replace that sensor and then have a really good bleed of the system. If that doesn't work then you have a problem somewhere around that valley gasket - I can't say whether you could have it the wrong way round or not but a quick phone call to one of the experts will point you in the right direction. Try someone like Turner Engineering or TVR Power.

Pete

[TVR Beaver]

Just look at the photo above.. you can fit it either way.....

does your stat have bleed hole in it?... I can't see how the manifould can air lock unless the stat has no hole in it.. when you squeeze to top hose can you hear the small ball in the stat pinging about?.. if it don't have one in, drill a 3mm hole in it to let the air escape through the stat...

also.. can you confirm your having the problem within 60 seconds... or could it be more like 3-4 mins?...

[IainGriff]

yes I can hear the ball in the stat, Not sure about hole in the stat, need to remove housing.
Probably wrong with the timing, maybe my perception and panic! although I'm sure it wasn't much more than a couple of minutes from cold to passing 90C on the gauge.
I'll have another go bleeding the system at the weekend and provide an update.
Thanks to all for the input

[IainGriff]

yes I can hear the ball in the stat, Not sure about hole in the stat, need to remove housing.
Probably wrong with the timing, maybe my perception and panic! although I'm sure it wasn't much more than a couple of minutes from cold to passing 90C on the gauge.
I'll have another go bleeding the system at the weekend and provide an update.
Thanks to all for the input

[TVR Beaver]

If you can hear the ball thing it has a hole. So no need to look. Unless you thinkk the stats stuck. Is the belt on right ?

[IainGriff]

The continuing saga:
serp belt routing OK, bled the short pipe on the left hand side of the inlet manifold - no air
so decided to check the thermostat which opened with boiling water
re fitted thermostat housing without the thermostat fitted
topped up system and completed ritual squeezing of pipes until no bubbles observed from my makeshift reservoir on copper pipe fitted to the header tank
started engine, engine temperature increased slower than previous attempts, after 3 0r 4 mins when approaching 90C I turned off engine, removed reservoir and pipe and fitted brass screw in header tank
restarted engine, temperature increased and I chickened out and turned off engine as temperature just passed 100C

Much scratching of head and remembered that I had snipped off the manky knackered last 4 inches of the single wire and insulation sleeve going to the temp sensor (fitted on top of the inlet manifold) and soldered a new 4 inch length of wire and connector.
So, I'm now wondering whether I have an indication problem rather than an overheating problem.
The question: should the wire to the temp sensor have an in line resistor and have I inadvertently removed it along with the manky section of wire?

Apologies for war and peace