The 60 million dollar question AKA the overheating bugbear

So my 1300 efi petrol mpv is going along perfectly well in the 2.5 years I've owned her until a garage visit to fit new wheel bearing / speedo

I picked her up, got 5 miles and she boiled, back to the garage; compression test reveals HG is ok, boil test reveals thermostat knackered, new one fitted - (by the way how DID they get that off when access to the third bolt looks nigh on impossible?) .. boils on first drive to work.. back to garage as I noticed the rad cap in the cab was split.. two new rad caps fitted. Ok for a few miles, boils. When I say boils, I mean I can hear it bubbling into the expansion tank.

Much fiddling, topping up, bleeding - she's ok for a few weeks; little hot here and there but 99% time is ok. Drive to Englandshire from IOW.. get about 50 miles.. boils. repeat of fiddling, fine.. drive home, boils and this time water pump knackered.

Ok, maybe that was the problem all along, yippee.. all new pump fitted, much repeating of fiddling, bleeding.. and she boils.

Facts what I know

If I turn the heater to cold position (not touching the fan)- that starts the overheat process.
It has a new water pump
It has a new thermostat
We are 99.9% sure it's not the head gasket (no evidence of that)
The pipes, hoses, etc all ok
Checked for corrosion around seals/pipes rad cap placements etc- all ok
The fan is working, and all electrics involved are all working as they should.

What we know
Water is not being sucked back up when the system cools

What we are wondering

There are two rad caps - both with 0.9 bar pressure
So in the endless problems of overheating/bleeding/filling cycle that these little vans are plagued with, could it be that the cap on the rad should be:
a) a higher bar
b) more of a plug than a pressure release system
The thinking/wondering is that surely if the heated water spews out of the radiator itself, surely it will just be sucking air back in?
OR.. does that little pipe feed back into the system and therefore force the other rad cap to expand into the header tank?

I know that this problem is inherent in our highjets, but if anyone has had a similar experience or can offer some new ideas for me, I'd be really grateful as I am completely stuck in this cycle and my van is currently unuseable... NOOOOOOoooooooooo!!!!

The cap on the rad should be a flat cap, not sprung on the 1.0 engine and I think on the 1.3 as well. The cap on the rail over the engine should be sprung, and 0.9 is right. If both are sprung you will get water expanding normally to the header tank and also escaping from the rad cap. When you hear the water bubbling, what does the temperature guage read?

Ahahh!!!

So the thinking about two sprung caps not being correct is right then! Thank you.

When it bubbles, the temp gauge is on high - right across to the right.
Last time we took her out (yest) she went about 6 miles perfectly ok, I turned the heater down (temp, not fan) and she boiled.

Drove back home after cooling (never drive her when hot) and she was fine - turned temp down as an experiment - she boiled

Yours isn't the typical overheating scenario as you've eliminated the usual cause - head gasket - and replaced the pump and stat. The other thing you might want to look at is the bottom of the 'cup' on the pipe above the engine, where the rubber seal of the pressure cap seals. If there's a rough surface caused by corrosion the washer won't seal properly and will let water pass to the header tank at a lower pressure.

TBH im leaning to rad full of crap, keeping the heater on cold eliminates the matrix which is a small extra rad in itself. Other than that, is the replacement thermostat the right opening temp?

Yes the rad should have a spring cap 0.9 bar, and under the passenger seat (uk vehicle) should have a spring cap 0.9 bar.

I have no exact answer!!

On my current one, it turns out that:-

Under the drivers seat cover is all this brown water residue:-



Caused by this little rubber bung thing leaking!



But also there was some brown scum under the passenger seat because the previous owner fitted the wrong rad cap which totally didn't fit, which resulted in this thing corroding thus causing my new rad cap to not seal:-



On stripping my engine I have found that someone has fitted a new water pump, and a new thermostat recently.... and obviously hasn't solved the over heating. Sounds familiar?


On conclusion:-

If you are not sucking back the water from the header tank on cool down and thus gaining an air gap, visible when you take the cap off under the driver seat - I'd say you have a leak somewhere. Which may be a pipe, a radiator, a head gasket or ever a BLACK HOLE!!!

And I would have a total guess that the air collects in your interior heaters heat exchanger, and when you move the heater setting the air gets pushed into the cylinder head sending you off up into over heat mode. Making me suspect the same silly rubber bung thing circled above but only a guess.

Before I spent any more money on your van or mine, I would 100% flush the radiator until it is clean, flush out the block etc, flush out the heater matrix. Then I would pressure test it using a foot pump and some pipe. Good luck! You'll need it

Great photos!

Thanks for all your input guys - great tips and hints.

After much head scratching we've come up with a solution and I'm about to take her for a test drive.. I won't write anything up yet
(not tempting fate or needing a scourer to get the egg off me face)

I'm feeling confident rodders..

I'll be back to let you know the ins and outies later..

Judging by the duration of this "test drive", I'd say it either went really really well, or erm well, they are sleeping in a lay-by.

Well, inspite of NOBODY offering any pictures to help with my 993 carb pipes I thought I'd put in a twopennorth re overheating.

I had had this continuously until I let it get too bad - resulting in head skim.
Do you have constant loss of water - it has to go somewhere!

I replaced thermostat, rad cap, checked pipes. However when I dismantled engine to repair the now obviously buggered cyl head, the first water gasket found in tatters was the water pump gasket!

The head gasket was shredded at a water passage area. This had not affected the compression, the engine had been running fine up until I ran without water(at all) late one night.

So if you're losing water continuously I'm afraid it's engine stripping to find that gasket.

Mine has run (temperature wise) faultlessly since the rebuild, never lost a drop.

ps I did pull the rad fan plugs and wires to install a manual switch. But this shocked the little animal so much it now runs the fan automatically all by it's self!

pps WHERE'S MY CARB PIPE PICS !!!

Reid wrote:Well, inspite of NOBODY offering any pictures to help with my 993 carb pipes...............................................pps WHERE'S MY CARB PIPE PICS !!!

Was going to post pics of MY 1300 EFI PIPES BUT DIDN'T THINK IT WOULD HELP

You are very kind sir - unfortunately you are correct. Maybe I should get an EFI?

I have a pipe from the manifold vaccum bunch disconnected - connect it to where it used to be on the carb top and the engine stops!
The engine runs well, both idle and acceleration, but with an unplugged vaccuum pipe!?
I did replace the plugs recently which were showing signs of great overheating - white with cracked insulators . . .

I too spotted your unanswered post but working strictly on 1300 versions I can offer no help or pictures really. If you think really hard about all those pipes, sensors and valves it will become obvious to know what goes where, it is after all a logical control system. The most important ones are the MAP sensor and the fuel pressure regulator. If you post some pictures up we can take some guesses which may help.

Plugs that are white with cracking means its running as lean as an Ethiopian on the atkins diet - if you don't resolve it you might be taking the head off again when it cracks between the exhaust port/valves/sparkplug thread, and this time you'll be trying to find a head to buy too. Or even better the end of the plug melts off and ends up down the side of the piston


Anyway, I have just got back from another car (yeah 11pm on a sunday night ) which is suffering the good old reliable misdiagnosis path as so many do, so excuse my arse hole nature. But I offer this simple train of thought:-

Replace only what you can prove to not work or be at fault.
Test the machine/system/etc to prove where the fault is.
Spend more time thinking than spending money.

Coolant systems can be easily pressure tested with air, and you will hear the leaks location, even down the spark plug holes if its the head gasket.

My first question answered before I even need to post about it.

Good thread, I'll have a good read when I get back to the van

Reid wrote:Well, inspite of NOBODY offering any pictures to help with my 993 carb pipes I thought I'd put in a twopennorth re overheating.

You too can have pics of the 993cc EFI pipes but I still think it won't be of use.

Reid wrote:
ps I did pull the rad fan plugs and wires to install a manual switch. But this shocked the little animal so much it now runs the fan automatically all by it's self!

pps

I did the same thing and got a shock when the fan kicked in on it's own the first time.

Duhh and heres me ranting about map sensors and fuel pressure regulators

Rich, you could give it a go - would be enormously grateful and let you know what the results are.

The CB41 engine starts perfectly, the choke works correctly and progressively, it accelerates as maybe a 3cyl 993 with 150psi per cylinder should and idles smoothly.
It doesn't lose a drop of water, the temp needle only rises occasionly to halfway (auto fan on) after a bit of work up hills.
As I mentioned I changed the plugs - the old one's were white with insulators cracked. Havn't checked the new ones yet.
I do max 55 to 60 for short periods, most driving is pretty light.

But only with a vacuum hose disconnected!

Wellll..

As you probably worked out, the test drives went fabulously well.. BUT The drive back home to IoW let me get les than halfway.. and guess what? Yup.. she boiled.. Arrggghhhhh!!! On the way back to her temporary home, she boiled 3 more times .. and then drove like a dream the rest of the way!

Sorry to take so long to post up, but return to work after hols was manic!

It isn't the head gasket, there is absolutely no evidence of that, she is retaining all the water/af, passed all tests and no sign of anything that shouldn't be there in pipes, hoses, etc etc.

Anyhoo what we have established direct from Daihatsu is that the cap on the rad should indeed be a 'plug' only (new one on the way)
it does make perfect sense that it would be spewing water/af out and sucking air back in from the top of the system.

So the next plan of action is a rad flush, fit new cap - bleed as per manual but also bleed using long hose attached to bleed point nr rad cap under passenger seat (this worked like a dream for removing trapped air)

I have read tons about these wee beasties online, it seems that each (non gasket) over heating problem has it's own quirky cause and equally quirky cure!

I've spent over £500, including a paint job on the roof, in the last few months.. with part prices rocketing, continued availabilty very iffy.. it might be approaching *that time*

I think the reason for the coolant systems on them being a bit odd is because of the top rad hose.

On all normal cars the hose from the top of the rad goes straight to the cylinder head, but because of the passenger/drivers foot wells on a hijet it swoops down first before entering the radiator potentially allowing the radiator etc to gain an air lock.

Don't give up, and if you want to 100% check that its not the head gasket or a cracked engine casing etc buy a bottle of block test. It reacts with the combustion gases if there are any absorbed by the coolant and changes colour.

Thanks HJ

Yes, they are uniquely designed, not least to make working on them a real !!

But I love my van.. so useful, so quirky, a bit wierd and lots of fun ..

Do vans get like their owners?


They should come with a sticker that says "You don't have to be mad to own one but..."

The_Magic_Bus wrote:Do vans get like their owners?

I think owners get like their vans! I too have a tendency to crankiness and boiling over - but I'm very economical to run and am good in tight situations!

The_Magic_Bus wrote:

Do vans get like their owners? ..."

Yeah, my back end's kinda rusty and i rattle a bit going over bumps

Logi wrote:

The_Magic_Bus wrote:

Do vans get like their owners? ..."

Yeah, my back end's kinda rusty and i rattle a bit going over bumps

That made me burst out laughing!!

Thanks for all the vids and help.. will keep trying - thanks guys

In the famous words of Andy.. I want one!

https://www.youtube.com/watch?v=38UcCF6Cvgs&feature=related

Reid wrote:Rich, you could give it a go - would be enormously grateful and let you know what the results are.

I will have to either find the pics I took for someone else or take some more will see what I can do.

Thanks Rich. I have the carb pages copied from a workshop manual - but they are too vague and difficult to be sure which goes where.
Andy

You do know that Rich has an EFI, eg one with injectors, map sensor, ecu and a throttle body etc?

Not sure how that would help you and your carb engine.

But after loads of digging, I'm not sure if any of these will help you. They are from the charades which sport roughly the same engine setup...

HighlyJetted - I looked at your diagrams and thought oh no they are from a manual - however - they are much better than those I have with far better explanations of what the tubes go to.
Thank you very much sir, rearmed I shall try my pipes again . . .
Andy