WATER TEMPERATURE and this bizarre Hijet overheating problem

With more than a passing interest in keeping temps down when I drove a Mini ( old British made rusty thing not the modern German thing  ) , there was a fluid you could buy for around £11 that when added to the coolant dropped the boiling point  . Just relooked it this past few days in relation to the Hijet's problem  -  and its still sold here in UK  -   Wetter Water Additive .
Has anyone tried this in their HiJet ?
Cannot believe that all the HiJets I have seen / asked about have issues with this overheating , and yet I hear of some ( few ) that have never had any
issue .    

Watching Youtube vids on seeking out fixes for overheating in other cars , the cooling system on the HiJet seems overcomplicated for what is a really basic control system on the internal combustion engine . Did Daihatsu know about this , or is it an accumulated with age problem that ahs only surfaced with age - Healthy looking but older water-pipes allowing air seepage into the system for example .  
Finding the Wetter product , I also found another  fluid - that at near £60 for 5lt is steered ( ) more for kit car and performance race driving .
I'd rather spend £60 on new pipes ( if I can find them ) , a thermostat etc etc etc .  I know what a kit car owner would suggest - buy a purpose made faster hi-flow radiator in aluminium , silicone pipes -  but we'd end up spending out £300 when all it should really need is a new pressure cap .

Read some of the other postings and you will see - there is a fairly simple fix to cure / prevent overhewating - this involves doing everything as described - myself I never use tapwater always DeIonised water and anti freeze 50/50 or premixed coolant. This isd because a lot of tapwater has a number of addatives that may very well attack head gasketts etc.
Upto now (touch wood) my van has not had any cooling issues and has completed Land's End to John o' Groats and the Vorth Coast 500 plus 3 highest bits of public roads in Britain (all in Scotland).
Jon

Hi and thanks for sharing westcoster. I have bought some stuff thats called MoCool from Motul wich seems to be same but cheaper and better available. All this stuff is mainily developed for racing where normal coolant is not allowed or such and you still need to lower boiling point an lubrication for the water pump as well as anti corrosion additive. But it also mixes with normal glycol based anti freeze and is said to be of advantage still.

So i will try it altough of course for a hijet its much more important to go to town on bleeding and radcaps and stainless hoseclips and fanswitch and thermostat etc... Dont think it will hurt though.

Let’s make this as simple as possible:

flush engine and radiator, bleed correctly, replace clips, replaced rad caps (making sure rad seats are in good condition), generally look after it with regular maintenance.

There think that just about covers it all! Using these waterless coolants in a Hijet only tries to mask any real issues. Do the job correctly in the first place then give it love and care and it will respond with some fun not heartache (just waiting for all the smutty innuendo posts now!).

The Hijet has a very simple coolant system, compared to most modern vehicles.

The fundamental problem lies with the foot wells. Between the top of the engine, and the top of the radiator are the foot wells, this means the pipes have to swoop down.

A normal coolant system has a top hose from the cylinder head straight to the top of the radiator. And an expansion bottle from the top of the radiator. This is not possible with a hijet.

Thus they have had to swoop the pipe work down, and have a double bottom entry radiator.

It's a very simple system but with a massive Achilles heal, any gases in the fluid will get trapped in the top of the radiator (like a degassing chamber), and when a large enough pocket of gas gets trapped there the coolant will no longer flow up and over the radiator.

The other strange thing with this series or Diahatsu engines is the location of the thermostat. Most normal engines put the thermostat housing on the end of the cylinder head outlet where the water is hottest. On these Daihatsu's the thermostat is in the side of the block. This makes them problematic to not opening, thus they overheat.

These are the 2 design choices by Daihatsu which really cause all of the woes for Hijet ownership.

Hi! i've been having issues with my overheating hijet as well. i've been reading this forum a lot which is so hard for me because english is not my first language, i am argentinian. my name is Celeste, nice to read all of you.

in several posts you talk about an 'article' that Raggy wrote about Woodies ultimate way of bleeding the system to get the air out but I CANT FIND IT. Can anyone pleeease link it below for me?

from what i've read from coments in different topics i kind of get the idea. the system needs preassure to get the water go up to the heater matrix. this is the reason why i've been filling it from the hose (yes, tap water, im so sorry i did this to you for so long dear hijet im still learning about you) but aparently the preassure of an elevated 'watering can' and the hose that fills tight in the radiator neck will do.

the part i dont undestand is why once the liquid is coming out from the small heater pipe without bubbles you dont close the heater at the same time you close that pipe with the little rubber cup and theeeen close the rad cap.

about my hijet story, overheating problems seamed to have been fixed for a while after we replaced the cylinder head (rectified the block and cleaned radiator) and we learned (kindof) about the filling method. but now it started to do some weird things. for example, the fan has a hard time bringing the temp down especially when im on the road on a stable speed 80 - 85 kmh. and in the city it appears to work a little better.
recently the fan starting acting strange, it kicked in at 90 degrees but it stopped too quickly, only a couple degrees less. so i change the thermocontact and it seems to work ok but still it is hard to bring the temp down. caps are new too.

im guessing with distilled water and that pink coolant will work better. just need the complete instructions to fill the system.

wow, wrote a lot. hope you understand my english and thanks in advance because all you wrote in this formus helped me a lot to understand my hijet.

Welcome, your English is better than some who are resident here! Have you seen this thread: https://hijet.forumotion.com/t3837-flushing-the-hijet

The 'guest' is the departed Woody.

Hi, make sure you use antifreeze in the coolant, may be worth doing a complete flush of the cooling system as you have been using just water, then refill with correct coolant, this will change the boiling temp of the coolant and probably help with the overheating issues. Good luck.