D4BF vs 4D56 Thermostats

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lrp374
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Joined: Sun Nov 23, 2008 9:56 pm
Vehicle: 91 Super Exceed
Location: Kamloops

D4BF vs 4D56 Thermostats

Post by lrp374 »

I had a D4BF Hyundai engine installed in my van in 2018 after an unfortunate incident in the fall of 2107. The engine has preformed well and with quite a bit of help from GrowlerbearNZ I have it tuned for a little extra power. I'm not sure if it's the extra power or the roof top boat and camping stuff I carry but most hills my speed is limited by the water temperature. I installed a temperature gauge this past spring with the sensor in the return rad hose. This gives way better response to temperature and I feel it's pretty accurate. I decided a lower temperature thermostat was in order!!

My first mistake was to presume that since the engine was identical to the Mitsubishi 4D56 I could just find the lower temperature thermostat and do the change. I wanted a 160F unit but would settle for a 170F unit. I did find a 170F unit from Mitsubishi and Rising Sun even carries them @ $ 70 each. I'm to cheap to pay that much so the hunt was on. I was able to get the relevant dimensions for the Mitsubishi unit ( see below ) and started the search. Tridon in Australia was the first real help as they listed all their thermostats c/w dimensions as well as some applicable engines. That lead to a number of UK sites where Gates and others had options. These varied from $20 to $40 plus shipping of course. I next started comparing some of the Mitsubishi alternates they were listing for their options for the Mitsubishi MD997606. This lead me to my favorite supplier RockAuto. A number of cross checks later I confirmed the thermostat for the Mighty Max 2.3 diesel was the same and they had both 160F and 170F units reasonably priced and the gaskets as well. All I had to do was wait – and in less then a week they were @ my door. Now I just needed the weather to warm up!

A month later I was ready to do the deed. I carefully took everything apart neglecting to drain the block so when I pulled the thermostat likely about 4 liters of antifreeze landed on the floor. Luckily I had a partial bag of absorbing stuff from previous incidents. I pulled the thermostat and it was totally different dimensions c/w a rubber gasket. I started the search for a new thermostat using Tridon again after some detailed measuring. I found Mitsubishi thermostats with the correct dimensions but couldn't find any with the lower operating temperature ( MD 164541 & MD170031 ). More cross referencing with RockAuto and I found a MotoRad 170F thermostat on a clearance for less than $2. I couldn't resist and a week later I had the new thermostat. It is the same dimensions and fit perfectly. ( I see now they are over $8)

I have been using it now for about a month and I can tell the van runs a little cooler under normal conditions and takes longer to heat up on long hills. Time will tell if it was worth the effort. If anyone wants the Mitsubishi units I have "in stock" c/w gaskets let me know.
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Dimensions for 4D56 thermostat
Dimensions for 4D56 thermostat
Thermostat001a.jpg (18.87 KiB) Viewed 261 times
2 low temperature thermostats
2 low temperature thermostats
160-170 Thermostats.jpg (71.27 KiB) Viewed 261 times
D4BF vs 4D56 Thermostats
D4BF vs 4D56 Thermostats
D4BF vs4D56.jpg (71.58 KiB) Viewed 261 times
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