diesel coolant temp and others

[momorris]

Hi all
Scrapped my LPG picanto due to a buid up of issues after 110000 miles ish from new. I have now moved to a peugeot 206 1.4 hdi. So far I have chipped it for economy and my last run saw 66 (uk) mpg compared to 58-60 ish normal. (Although its now winter and the normal mpg was during summer months).

Planned mods are floorpan. Mudflap delete.

I currently run a partial grill block but the engine temp sits at 75. Would blocking more be a god move. Basivally does a hotter diesel run better.

Cheers

[Diesel_Dave]

If your grille block affects your final coolant temp, then you've blocked off too much grille. The grille block should make the engine warm up faster, but not affect the final temp.

Your thermostat should control the final coolant temp by regulating the flow rate to the radiator. If your grill block has affected the final coolant temp, that means the thermostat is full open and has lost the ability to prevent overheating.

[momorris]

Cheers for the reply. The grill block doesnt affect final temp. The 75 degrees seems really low though. I thought the thermostat might have been stuck open at first. I know from other forums that people were concerned when they first got the car about how cool it runs.

If a diesel does run more economically when warmer what would be the best way of getting it warmer. I think ill chexk with peugeot to see if they have a higher temp thermostat as well.

[UFO]

Get a higher temperature thermostat. Most diesels I know spec a 85C or 90C unit.

[tjts1]

Get a colder thermostat than stock. Diesels are more efficient running cold. You just want enough heat for ignition. Colder intake air will be denser and cause a leaner mixture for a given amount of fuel.

[Piwoslaw]

Originally Posted by momorris

I currently run a partial grill block but the engine temp sits at 75.

That is low-ish. My turbodiesel (1.6 HDi) would hardly ever get above 78°C without grille blocks. With both grilles blocked the coolant gets warmed up much faster, stays 78-80°C, and keeps a higher temp for longer (eg after traffic or hill climbing), but my driving has become so efficient that the coolant temp drops back down. At outdoor temps below -10°C the engine gets cold if I turn on the heater, even though the I've put insulation on the engine.

As for higher temps you should be OK. Diesels like to run hot, my idle fuel consumption is 0.48-0.52 liters per hour @90°C, compared to 0.52-0.56 l/h @ 78°C.

Originally Posted by momorris

If a diesel does run more economically when warmer what would be the best way of getting it warmer. I think ill chexk with peugeot to see if they have a higher temp thermostat as well.

I have thought about this, but I'm not sure if PSA has a hotter t-stat that is interchangeable. You might be able to DIY a swap (like this: Modified Thermostat for higher MPG's...) if you can find a hotter t-stat that will fit. My engine's t-stat is inside of a plastic housing with the temp gauge and I'm not sure if it can be opened

Originally Posted by momorris

So far I have chipped it for economy and my last run saw 66 (uk) mpg compared to 58-60 ish normal.

Can you give more details? Here is a thread:
Eco remapping aka chiptuning

Originally Posted by tjts1

Get a colder thermostat than stock. Diesels are more efficient running cold. You just want enough heat for ignition. Colder intake air will be denser and cause a leaner mixture for a given amount of fuel.

That's the first time I've read that a diesel likes to be cold! What I've always come across is that diesels like to be hot, but with cold air intakes. Both for efficiency and performance.

[momorris]

Thanks for the replies everyone

Your thermostat should control the final coolant temp by regulating the flow rate to the radiator. If your grill block has affected the final coolant temp, that means the thermostat is full open and has lost the ability to prevent overheating.

I now believe that the thermostat is duff. The grill block does affect final temp and even with full block it only sometimes gets to 90 but drops straight away once moving and even if I put the heater on.

I have thought about this, but I'm not sure if PSA has a hotter t-stat that is interchangeable. You might be able to DIY a swap (like this: Modified Thermostat for higher MPG's...) if you can find a hotter t-stat that will fit. My engine's t-stat is inside of a plastic housing with the temp gauge and I'm not sure if it can be opened

My thermostat is also in a plastic housing. From reading around I think it's only the one type available.

With the higher temp the grill block has given me though and my new driving style my last tank was 71 mpg. Stock combined is supposed to be 65.7 so I'm smiling. (Hope we are still on winter diesel). Today I looked into the floor pan but conditions and time don't allow it yet. I have now removed the mudflaps and fitted a front dam and rear tyre spats so I will be watching the gauge with intensity next week. I can't get a scan gauge as the car isn't obd which is a little annoying.

I'll post in the linked thread about the chip.

[ksa8907]

Simple thermodynamics, if that exists. Hottest combustion possible, coldest intake possible.

[UFO]

Originally Posted by tjts1

Get a colder thermostat than stock. Diesels are more efficient running cold. You just want enough heat for ignition. Colder intake air will be denser and cause a leaner mixture for a given amount of fuel.

No way. Lean is irrelevant as fuel mixtures are not controlled. Diesels make more power and are more efficient when run hot.