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jcbjs 260

V8 engine specialist required.

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Hi, I have just rebuilt my engine but have a coolant problem. When the engine is made to excelerate hard it wants to expel coolant from the overflow. When the engine is made to work I can see steam from the engine in my rearview mirror and straightaway the temp gauge starts rising. This problem has only started since rebuild. Now I have bleed the system nurmous times so I can't see this being the problem. No vapour from exhaust when warm. I have removed the thermostat and check it to make sure it is opening ( placing in boiling water) and it seems to work perfect. The car can run in the garage going through thre cycles starting the fans, and cooling etc. The heater in the car is preforming perfect, therefore I cannot see there being a problem with the water pump. I have preformed a pressure test on the coolant system again perfect. I also had a dye test done twice by two different mechanics and again proved negative. Also had a new 3 core radiater fitted during rebuild. No colant in oil etc. I would be extremely greatful if someone could point me in the right direction.

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Does it overheat when driving normally (conservatively)? My first guess, aside from the obvious bleeding which you mention has been performed, is that perhaps you have a coolant hose that is collapsing on hard acceleration. My guess is the intake hose nearest the engine as that hose will take the full brunt of suction from the waterpump where the radiator to coolant pipe hose should be less subject to collapse. I'd make sure that your coolant pipe to engine inlet hose has a spring in it (if they still do that), or isn't deteriorated to allow collapse.

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The coolant hoses to and from the thermostat housing are very short, so I would be amazed if there was any chance of collapsing the section based on suction from the water pump.

Who fabricated the radiator? Is it s proven part or a custom build? Could it be that there is a restriction in the radiator that is the source of the imbalance?

The curious part is the steam that you are experiencing. I am surprised that you cannot see visible signs of a leak if you have steam. Are you sure that it is steam and not oil which may be residual from the build?

Cheers,

Mike S


1996 Esprit V8, 1998 Esprit V8 GT, 1999 Esprit S350 #002 (Esprit GT1 replica project), 1996 Esprit V8 GT1 (chassis 114-001), 1992 Lotus Omega (927E), 1999 Esprit V8SE, 1999 Esprit S350 #032, 1995 Esprit S4s, 1999 Esprit V8 GT (ex-5th Gear project), 1999 Esprit V8SE ('02 rear)

1999 S350 #002 Esprit GT1 replica

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Thanks for the replys. yes the car does run ok at moderate speeds, will check the front pipes today but as I have just replaced the radiator the rubber pipes all looked in good condition.

Yes Mike, It is steam and no leaks.The coolant is dispersed from the overflow pipe onto the top of the exhaust. I agree with you the pipes are too short to be sucked in. I also think you are in the right line with the radiator. It was fabricated in a local shop, the guy is excellent at his work which is why I have not pulled it out of the car. I am running out of idea's fast but I am beginning to think the radiator is at fault. To be honest it is doing my head in. thanks again for the pointers.

Edited by jcbjs 260

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Right, I have now tried everything I can think of and now planning to remove the engine and heads from the car this weekend.I ran the engine without a thermostat and the temp gauge barely moved which puts the radiator in the clear.Fitted a new thermostat,new pressure cap (20psi)and the problem persists. Engine runs fine until made to accelerate hard, I can then see the coolant dispersed onto the road(rear view mirror) and within a minute the temp gauge goes crazy and the heater is lost.The only thing I can think of is I did not use genuine lotus head gaskets. I don't know if this would cause this problem or not. Any info that might concern this problem is more than welcome as I have not a clue what I am now looking for. P.S.the engine does put white smoke from both banks when started from cold but disapears within a few minutes.

Edited by jcbjs 260

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Hi Leonard,

I am no mechanic but from what you have posted, I would say it was head gaskets. I don't know anyone else using non Lotus head gasket? Maybe someone else can verify this? Mike S, can this be a possibility?

Have you spoken to Pete about this?

David

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Thanks for the reply Dave, Yes I have talked this over with Pete. He didn't think it would be caused by non genuine head gaskets but anything is possible. The only thing is a dye test was done for exhaust gases in the coolant and it was negative. I am not sure how accurate this dye test is though. To be honest I am a bit pissed off with it at the moment but suppose I have no choice but to try to find the problem. thanks again for the reply Dave.

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A bit of lateral thought (as I have no idea if its possible..)

The turbo cores are watercooled, is it possible that they could be leaking when spun up and thereby causing the system to pressurise?

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In extreme cases the lines can get blocked as they are pretty small and rust too! I have heard of over heating problems caused by this.

David

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I


1996 Esprit V8, 1998 Esprit V8 GT, 1999 Esprit S350 #002 (Esprit GT1 replica project), 1996 Esprit V8 GT1 (chassis 114-001), 1992 Lotus Omega (927E), 1999 Esprit V8SE, 1999 Esprit S350 #032, 1995 Esprit S4s, 1999 Esprit V8 GT (ex-5th Gear project), 1999 Esprit V8SE ('02 rear)

1999 S350 #002 Esprit GT1 replica

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A bit of lateral thought (as I have no idea if its possible..)

The turbo cores are watercooled, is it possible that they could be leaking when spun up and thereby causing the system to pressurise?

This has crossed my mind but have not heard of this happening. Thanks for the reply Pete

In extreme cases the lines can get blocked as they are pretty small and rust too! I have heard of over heating problems caused by this.

David

Thanks again David, I have replaced the turbo lines with replacements from Pete.

I

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And the crowd goes wild! Yippee! Another Esprit back on the road. :thumbsup::animier:


Being second is to be the first of the ones who lose.

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