Sunday, May 09, 2010 at 18:33
Okay, just so you have all the facts......
I used to own a Patrol with 4.2TD which used to get quite hot (coolant wise).
I won't
bore you with a blow by blow of all the things I did, but a couple of them will be of interest to you (I hope).
I fitted (amongst other things), a Thermoguard EGT (exhaust gas temp) gauge with senders both before and after the turbo. I also fitted a reasonable quality coolant temp gauge (VDO) with the sensor in the top radiator hose.
After owning that vehicle for 6 years and having "studied at length" the various relationships between various components under the bonnet I can report as follows:
1) There is not necessarily any corrolation between coolant temps (as would effectively be measured by your proposed fitment of a TM2) and the temp of the turbo and/or exhaust gases. For example, if your vehicle's cooling system is in good condition, you could be flogging up a steep
hill with a good load on and the coolant temp might not necessarily show ANY increase. However, the EGT gauge will quite easily rise from 350oC to 550oC in the space of 3 klicks; and that is perfectly normal and acceptable. On the other hand if the coolant system is blocked or has some other issue, it is possible to see the EGT gauge staying "normal" while the coolant temp could rise to 100oC (or above).
2) In 99.9% of situations, I noticed on the EGT gauge that even after having been driving for several hours at highway speeds (with say a EGT gauge reading of 550oC in the manifold or about 350oC in the dump pipe, below the turbo), that by the time I entered a town, slowed down to 60k/h for one of 2 klicks before pulling up for lunch or at a servo to get fuel (for example), the EGT gauge will have easily dropped to around 250oC (which is the temp at which I was happy to shut my engine down).
So, to conclude: by all means fit a TM2 (I have one on my Chev 6.5 V8 diesel's block). But, PLEASE don't automatically rely on it's reading to tell you what the turbo temp is. Secondly, I really don't think a turbo timer is necessary. As mentioned, in 99.9% of instances, even after a long highway drive with full load, the turbo will have cooled sufficiently by the time you pull up and want to stop. The only time I can think of that this wouldn't be the case is (for example) if you got pulled up by the cops (or because a kiddy was about to puke etc) right at the top of a large
hill....your EGTs would be elavated above normal and it would be wise to allow the engine to cool down for a minute or so before shutting it off.
EGT gauge before turbo timer in my opinion.
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