mgf.be

[Thomas]

The system does not function well in cooling circuits with a radiator a long way from the engine in the cooling path, or for engines constantly seeing high engine speeds .The problem arises when the engine is put under heavy load, causing high engine temperatures that are not immediately read by the thermostat because cold water in the radiator and hoses has to pass the thermostat first. This can cause enormous thermal gradients across the engine, causing both distortion of the head and block and also gasket failure. The vehicle which suffered most from this was the Land Rover Freelander. Apparently, the typical owner for this vehicle is the middle class housewife and mother who use it for large numbers of short shopping trips to the supermarket!! Being heavy and 4x4, the 1.8 litre K’s tend to be pushed very hard from cold. This results in the engine getting very hot before the water can circulate and open the thermostat. Result – blown gasket. Early last year, Rover introduced a new thermostat, the PRT thermostat that will open with pressure as well as temperature, the result is that it opens much more quickly and prevents this thermal shock across the engine. There still appear to be problems with the Freelander, amid concerns that Ford have already executed a cost down on this new thermostat. However, it is quite apparent that as soon as the thermostat is moved to the output on the engine that temperature related gasket failure no longer becomes an issue. It is something of a surprise therefore that the Ford engineers concerned with the installation and performance of the K in the Freelander do not adopt this simple approach. The PRT thermostat is also a very expensive item that must be an issue with such pressure for cost downs. However effective the PRT thermostat is for a road car, a far more effective solution for any engine used on the track, and in fact any Elise with its problematic long coolant hose runs is to move the thermostat to the output side of the engine. Both Elise Parts.com and QED do inexpensive remote thermostat housings for this purpose. When one of these units is employed, the thermostat is measuring the engine temperature and is therefore able to control the coolant temperature quickly and sensitively.

Removing the thermostat altogether, as currently practiced by some, is no solution, firstly because engine warm-up becomes protracted, with all the implications for premature engine wear and secondly, because the engine temperature is at the mercy of the pump speed, if engine speed falls, the coolant in the radiator will cool disproportionately, then as soon as engine speed builds and engine temperature with it, the pump speeds to sends a mass of very cold water from the radiator suddenly to the engine. There is no thermostat to even this process out so the engine is repeatedly subjected to thermal shock. Bad for the head, bad for the block, and sooner or later the gasket will go. Fit the thermostat to the coolant output and the extreme temperature gradients that beset the engine when used on the track are significantly mitigated. Modification of this coolant path is something that Lotus should have done with all the K series engines in all their Elise’s, This would have then prevented any gasket failures.

Bron:www.sandsmuseum.com

[Jupilerman]

Lap daar gaan we weer met het HGF en PRT verhaal

[Sir Charles]

Is wel interessante info die ik hier lees.

Het gaat hier gelukkig om een garantiegeval.
Ik heb de wagen 4 maanden geleden bij een handelaar gekocht. Sinds het begin had ik een verbruik van koelvloeistof dat hij niet kon oplossen, tot ik uiteindelijk de zaterdag voor Zandvoort wolkjes zag drijven in het koelvloeistofreservoir.

De wagen is ter diagnose/herstelling binnengebracht bij een ex MG-Rover dealer.
Mijn aandeel in de kost is gelukkig beperkt tot de werkuren (enkel garantie op stukken).
Ik ben nu wel tevreden dat er een gloednieuwe motor inzit waarvan ik 100% zeker de historie weet.
Eigenlijk een geluk bij een ongeluk, want de distributieriem moest sowieso binnenkort vervangen worden (4 jaar), dus eigenlijk is de kost voor mij zo goed als gelijk. Alleen heb ik nu natuurlijk wel een compleet nieuw blok. Er mag ook een positief kantje aan de miserie zitten, he

[Thomas]

Lap daar gaan we weer met het HGF en PRT verhaal

PRT

en nee deze staat niet in de lijst

[Jupilerman]

Pressure Relief Thermostat:

lees dit artikeltje even

http://web.tiscali.it/elise_s1/

greetz