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3.5 V8 Engine Overheating


Guest Ian obrien

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Guest Ian obrien

Morning all,

 

I recently had to have another 3.5v8 engine fitted which came from a running range rover which was not over heating. For some reason my car keeps over heating. My mechanic is scratching his head a bit as he as tried everything to try and keep from over heating but the strange thing is he had originally tested it in his unit twice leaving it run for 20-30 mins a time and the temperature stayed bang on halfway in the normal but after about 10 mins of me driving it home I had to pull over as the temperature was starting to get a bit high. At first my mechanic thought it was trapped air but its still overheating. Any ideas?

 

Thanks

 

Ian

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Idleing away with the bonnet off on something like an alloy Rover may very well not generate enough heat anyway, so I wouldn't assume standing in a unit for 20 minutes as necessarily confirmation it was all good.

 

I assume it was just a straight engine swap - nothing else changed during the process.

Start with the basics. Water pump ok? Thermostat ok?

Feel around the hoses for non-hot spots?

How does the radiator feel - hot by the inlet hose, cooler by the outlet? Or hot across it all, or even worse cold across it all?

Pump the hoses to try and get any air out

Check bleed points, if there are any

No blockages?

After the engine swap are all the hoses definitely on the right way :D?

If it wasn't overheating before and all that's changed is the engine then logic says :

1) Air/blockage in the system

2) Something incorrectly fitted

3) There is some history to the engine that you're not aware of, given it allegedly never overheated in the rangey :)

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are you sure it is overheating? with the new engine you'll have a different temperature sender, which is unlikely to be the same resistance as the old engine's.

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Guest Tim Norman

Can the hot air get out from under the bonnet? my bonnet is very well vented!

 

Is the rad big enough? Mine fits in the nose cone but no air get passed it

 

Is the thermostat correct, I run a 74 deg in mine.

 

4L 275bhp Rover V8 and a thermostatically controlled 14" fan and it sits at 85-90 deg all day long when the loud pedal is pressed!

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I'm confused by the suggestions. Can I clarify one thing with the original poster.

 

This car had a V8 engine in already, right? You've just swapped for a replacement engine? You said "another" so this implies that everything was fine before the engine swap, right?

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Seems strange that it would overheat when there is air being forced through the radiator but not when there is no airflow. Is the temperature sender in the same place on the new engine, does it actually boil up? My engine in my 101FC land rover always ran with the gauge reading just off the red but it never ventured in there whatever I did with it. Presumably you have ditched the viscous fan in favour of an electric one. I guess the first thing you have to do is look at what has changed between the two installations and work from there.

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Guest Ian obrien

Thanks for all coming back to me. I'll get my mechanic to send a photo of radiator and the radiator is right in the nose of the car.

 

You'll have to excuse me guys as I didn't actually build the car and bought for a bit of fun and its been a bit of a nightmare since purchase.

 

Just to clarify the engine that was in the car was a 3.5v8 and all that's been done is swap the engine as the old one was very tired. nothing else swapped same radiator, fan etc..... but my mechanic did say it never had a thermostat in it even with the previous engine. Does that sound strange?

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Guest Ian obrien

No it never over heated before. Its just strange how it didn't over heat when he left It running for 20-30 mins on the spot but when I drive for 10 mins its starts getting hot??

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I'm just guessing here, but it may be that he just left it ticking over - probably with the bonnet off - in which case it's not entirely beyond belief that it wouldn't be doing enough work to get that hot anyway.

 

But the key bit for me is that old engine didn't overheat, new one does. Assuming the engine is "good" (ie. timed, fuelled correctly, water pump is working) then I'd suspect air in the system somewhere, or something has accidentally been introduced (or missed) during the engine swap... kinked hose, for example.

 

I'm not savvy with the RV8, is the water pump belt driven and if so, is everything OK in that sense...?

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Guest lotusPaul

Do you know what carb your running? If its lean then you will get higher temps, on the other hand if you richen the mix it generally helps cool the engine.

 

Im a big fan of wrapping or coating the exhaust manifolds, it keeps heat in and speeds the gasses which helps with performance, and also keeps under bonnet temps down too.

 

The hot air has to escape, not only from louves etc but a commonly over looked area is between rad and engine.

 

Pics will defo help. Do you have good fresh coolant, at correct level?

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