Overheating Hijets

Obviously a common problem, i have just bought a beat up old Hijet 998cc efi, on driving home it overheated twice, and more coolant than water came out, on checking the van over when i got home, i discovered that the previous owner had obviously suffered with this problem before, ie new rad fitted with seperate fan and switch, thermostat removed, coolant not water in system. Back in the 80s i had an old vauxhall viva which had the same problem, this had been stood unused for quite some time, as i believe the Hijet had as well. This is the solution to the overheating issue on these vans. As you know the engines are prone to rust, as are the rads, pipes etc, and this causes a major problem because the residue rust sits within the water channels encased within the engine, which in the loop, should cool the engine after being returned, cooled and recycled via the radiator, courtesy of the water pump run by the engine. If the residue gathers in these small water channels, you get a blockage, which inevitably ends up with the water not being able to flow correctly, getting to boiling point, and oooppppss, overheating. The system is very similar to a central heating system in the house, and as such, needs sometimes to be " purged". The way to do this is to completely empty the system by removing the the tap on the radiator, normally found at the back of the rad facing the engine, the water should then empty onto your head, if your dumb, you will stay there, but its better to move. once the system is empty, get your hosepipe, and stuff it into the rad filler cap, ( engine off), run the hose for about 20 minutes, or until the water runs clear, double check under the passengers seat that the water is constant in the pipe. While you are putting the water in via the hose in the filler cap, you can start the engine, just to help pump the sytem clean ( do not let the system go without water whilst the engine is running or you will be in the shit). After you have done this turn engine off, and find a strong descaler ( i used lifeguard toilet descaler) put about half a litre in the radiator and a good squeeze in the pressure release cap under passengers seat ( engine off), replace plug on radiator and fill system with water ( engine off). leave for about 10 minutes so the descaler can work its way through the system, run engine intermittently to assist in gettin it round the loop. after ten minutes take out the rad tap, empty the system, and completely purge by again shoving the hose in the front rad filler and running cold water through it for as long as it takes to get rid of all the descaler. Fill system, bleed it, and hey presto, no overheating, no temperature gauge off the scale, and Hijet runs like a dream. Also DO put the thermostat back in for winter, these things dont like too much cold, or too much hot. Hope this helps.

welcome to the site, always need more info on these wee vans. good read of the article there.

nice one. mine after 2 days of driving has over heated. got a new thermostat on order and replaced the rad cap as the seal was a bit iffy. I'll get myself down 99p store tomorrow and get some descaler to give it a try, will be a lot cheaper than rad flush.

I'm guessing there's no advantage or disadvantage to flushing the system with or without the thermostat. Didn't realise getting mine out was going to be quite such a chore (alternator out, centre handbrake member out etc)
Aim was to get the old one out which I thought was sticking. But wait oh dear there wasn't even one fitted... Great.

Can't really be arsed to put it all back together without one to flush it then dismantle it to put the new one back in again.

998cc mines under the rear "hump" for access...to the left.

leopard_pagan wrote:998cc mines under the rear "hump" for access...to the left.

wish the 1.3 was that easy. LPG made it worse. Manual didn't mention anything about removing the alternator but couldn't see any other way of getting to the third bolt.
Thermostat arrived, don't like the way it sits between the head engine and the flange. leakage waiting to happen

Is that the heater bleeding plug?

the heater bleed should be at the top of the system the pic you out up shows the engine bay the heater matrix is in the dash and the highest compont of the system which is why the air gets trapped up there and the bleed is to let it out.

Yeah thats the only thing I can find thats in the same place as the manual describes. The only thing I can think you do is pull the pipe off where the arrow is and raise it in the air. Thats what I did anyway which seemed to work. I've got a bit of an extension to make sure its deffo the highest point when I finish flushing and top it up tomorrow it tomorrow.

When I was fast idling today circulating some denture tablets around the system it seemed to work as it should with the needle dead central unlike the last time I drove it.

I have a bypass switch as the auto one dosnt work but anhoo yesterday i had to take grill off and the plastick bits broke so i chuced it in the van and went off i was amazed at much better it ran temp was down below half all the time so now ime going to drill loads of holes in the grill to let the air straight on to the rad

I'd recommend using some block test fluid to make sure there is no combustion gases in the coolant. Save you pissing in the wind when it turns out the poor coolant system has done the head gasket or cylinder head. Very handy stuff is Block test fluid.

Trying to flush out a coolant system with the thermostat in place wont work very well as it will be closed until the water hits 90 degrees.

And correct, engines need thermostats, otherwise they should pretty much never get beyond luke warm.

Also I would always recomend changing the metal coolant pressure cap (radiator cap that isn't on the radiator on a hijet) as when they have been on and off a load of times the spring goes knackard thus stopping them from working at 1.3 bar or whatever its rated too. After all this stops the hot water boiling into gas at 105 degrees or so.

Hi all, this is my first post. I recently bought a 1.3 dual fuel hijet i believe it belonged to Matt a couple of owners ago. I'm wondering whether it's operating correctly or overheating. On average the temp gauge sits at about 60-65%, it shoots up when sitting in traffic and at about 85-90% the fan clicks in very breifly. once it has shot up it does come back down but sits around 70%. Is this a normal operating system or does it seem too high?

Sounds too high, when I fixed that one it always ran hotter than my other one.

I bought the thermostats from the same shop at the same time. But they seem to have a different operating temperature.

If it doesn't lose any water I would suggest it is just a thermostat issue which is very common.

My first port of call would be to put a new thermostat in it, and see how it goes.

I know your in nottingham, but if you came to me here in Crewe I would put a new thermostat in it for nothing.

I was thinking it was the thermostat or at least start with the thermostat, i remember you telling me that you had put a new one in and it ran higher. it doesn't seem to lose water. My gut tells me that it is running too high so i want to resolve it before it does any damage. She's a beautiful little van and i would like to keep her running well. I have owned air cooled VW's my entire life and have managed to learn how to dismantle and rebuild them, motor included. I haven't had to handle water cooled motors/radiators really so i am keen to learn. So i would like to bring her to you and watch how you change the thermostat, no doubt i will need to do it in the future again:)
Next Sunday is probably the only chance i will have to drive to Crewe as June is totally booked up. How does that suit you?? cheerz

If sunday is all you've got then I will make time for you, but if your coming I need to know asap so I can get one from the motor factors as friday is the cut off time for getting one to the branch.

Either this sunday or i am free the weekend of june 8th&9th. If you order the thermostat i will give you the cash for it. If the weekend in june works better for you that's ok with me

I'm off down the motor factors to get a refund on a set of brake drums, so I'll get a thermostat while I am there. Lets have it this sunday! No time like the present.

I have your new thermostat on my desk!

wow fast awesome! OK, your address is the same as your mailing address?

Well it was good to see Zaffy and my old red LPG hijet.

Especially as it is looking better than ever. It's had a new driver side sliding door so it's not dented any more, a new set of mats and a proper good polish n touch up here and there.

Fitted another new Nipparts thermostat - same temp range as the old one.

Now it runs right bang in the middle of the temp gauge and the fan seems to kick in earlier.

It would seem to me then there are some quality issues with these Nippart thermostats, as:-

the one in my current van runs very cool - about 1/3 of the way up the gauge
the old one in the red van ran about 5/8th the way up the gauge
And the new one runs exactly 1/2 way up the gauge

My local motor factors offer a blueprint thermostat as well but they want about £25 for one

I have also see these on ebay by Gates @ £27 but listed as a 78 degree
http://www.ebay.co.uk/itm/Thermostat-Kit-Daihatsu-Piaggio-Gates-TH29478G1-/400450392226?pt=UK_CarsParts_Vehicles_CarParts_SM&fits=Model%3AHijet&hash=item5d3cb410a2

The Nipparts ones are 82 degrees.

Next one I need, I'm going to try one of these 78 degree ones


Micksgarage.com do this Quinton Hazel one for £35 and thats listed as 78 degree http://www.micksgarage.com/proddetails.aspx?pid=1060366&pk=AE6A2

While there are some 84 degree ones one the market from Valeo and also Herth+Buss at about £28.