overheating 2L petrol - any new ideas?

[jonno_]

I am at my wits end! My lovely 2L petrol 2001 bongo overheats when she has been on the road for half an hour and tries to do a hill. She generally loses significant power going up hills even when not fully loaded. If we rev her over 3k she overheats. Her engine temp gauge goes up, we stop and open the bonnet and the water is pouffing out of the overflow of the header tank. We let her cool down before carrying on.

This is clearly not normal. Should we just not rev her on the hills?

We've taken her to 2 separate Bongo specialist garages. The first garage tested the cylinder head and had it planed as it was pitted. They put in a new thermostat. Though when examined later the shaft seemed bent (ie leaving it open).

Less than 200 miles later she overheated. Although they have a good reputation, we wanted a second opinion and better customer service so didn't send her back there. We'd paid £750 for their work. We took her to a second specialist garage (who normally work on diesels). They did a combustion test and found co2 in the coolant when running.

They didn't trust the first garage so sent the cylinder head off to a different specialist company for pressure testing, who gave it a clean bill of health. They couldn't find anything wrong but once they put her back together they did another combustion test and fitted a new genuine Mazda head gasket - no co2. They tested the water pump and flushed the cooling system and radiator. Less than 50 miles later, she overheated. The bill for the second garage is £1000.
We spoke to the garage and at the moment are just out of ideas as to what to do next. They've suggested a completely new engine.

Does anyone in the Bongo forum have any fresh ideas?

If we had to go for a new engine, would a 2.5L petrol engine fit? What else would we need to change?

What's the opinion on re-use of head bolts in a 2.0 petrol? They've probably not been replaced.

I love my Betty bongo, but she is proving high maintenance!

Thanks for all suggestions!
Sarah

[Gasy]

Hi and welcome
Sounds like your having problems
Someone with more expert advice than me will be along to help
But with all that work done I wouldn't be thinking of a new engine

Has the water pump not been replaced yet
That's a major part of the cooling system
And radiator
Good luck

[Bob]

Hi Sarah, and a warm welcome to the Forum

Sorry to hear of your expensive problems, I can only second what Gasy says but we do have some very good techie types here.

Thorough flush plus new rad and pump would be worth a go, and I doubt a V6 would be an easy fit.

[New Forest Terrier]

Is this the 2ltr that has been at Discount Trucks this week? There are a series of photos on Mazda Bongo Owners of what sounds like the identical problem being dealt with on a 2ltr.

If it is not I suggest you give them a ring. Fred - Paul Horsfall at Discount Trucks has dealt with a lot of petrol Bongos and can tell you how he sorted out the problem

[teenmal]

Sarah,I feel very sorry for you, it looks like you are being led up the garden path by these "Bongo Specialists" I would not like to fork out that sort of cash and not have the vehicle cured.

You should have returned the vehicle to the "First "Bongo Specialist" or at least contact them about the bodged thermostat.

It would probably be best to contact these garages and Complain, get an answer from them then take it from there.

Best of Luck

[jonno_]

Hi all
Thanks for the replies.
Yes, Betty has been with Gerry and Fred @ Discount Trucks trying their best to sort her.

The water pump has clearly been replaced at some time, tested and it works fine.
Rad and all cooling system has been flushed and seems to flow well.
Thanks for the ideas, keep 'em coming!

[New Forest Terrier]

Every sympathy. Its a lovely looking Bongo. Something very wrong here and longstanding from the state of the thermostat. With nothing leaking and water flow fine most of the obvious causes of overheating have been dealt with. You obviously have been very unlucky and got one probably bodged in Japan.

The 2ltr should be so much simpler than the V6 to troubleshoot. They are now coming over in larger numbers so a second hand engine should be possible to find.

[Northern Bongolow]

sounds very peculiar for a 2 ltr, the garage named has a good name in repairs, can you pm me the name of the other garage mentioned please.
has the bongo had a coolant system pressure test done, this will show that the system is water tight and not letting in air, if the system is not air tight it will allow the coolant to boil at a lower temp than if it was under pressure. replace the cap on the expansion tank too, this is a service part that should be changed fairly often but is often over looked, if the cap is venting early this maybe your problem, cheap fix too.

[Simon Jones]

One good thing about the 2 litre is that it is self-bleeding via an extra pipe on the expansion tank:

[g8dhe]

Somebody hasn't fitted the wrong pressure cap have they ? Should be labelled 1.1Bar but its not unknown for 0.9Bar ones to be fitted ....

[jonno_]

Thanks Guys.
On second expansion tank cap (@ 1.1bar) and also swapped one for the rad cap so think we can rule that out too.
Currently thinking it might be the re-used head bolts - I know those for diesels are supposed to be replaced after each use, but what about on the petrol 2.0? Anyone know? Might make sense as its only under load (up hill) that we normally hit problems.

Failing that I can only conclude something amiss in the block causing the overheat - blocked water channel(s) perhaps.
Anyone seen that before?
Thanks for all the help and advice!

[mikeWalsall]

Just reminded me .. I lost the cap from the plastic coolant bottle cap from my V6 twelve or more months back ..

As the only caps I had 'knocking around' where 0.9 bar for L/C motor bikes, I used one for a 'temporary' measure ..

Never been a problem I have to confess .. fitted / forgotten until this post reminded me ..

[Transporterman]

I think it would be worth getting the radiator flow-tested by a radiator specialist. There isn't really a reliable diy test. They don't often get blocked these days because modern coolants keep cooling system cleaner but it's possible and it could cause your symptoms. What mileage do you have on your van btw?

[Simon Jones]

The manual for petrol engine just lists a tightening torque rather torque + 1/4 turn or whatever the diesel engine process is, so they may not be stretch bolts. I don't think bolts would be the cause of the problem to be honest.

When going uphill the engine is under more load and you're often going slower so getting less airflow through the radiator. I would be tempted to set a proper temp gauge on the head and see what its actually doing. Are the rad fans coming on when it gets warm? On my V6, the temp of the coolant drops noticeably when the fans are on.

The cap on the radiator should not have a pressure relief valve, just the one on the header tank. They'll both be marked 1.1 but the yellow one has the extra spring loaded valve underneath. The extra height can be seen here with the bigger shadow:

[rita]

This looks like a typical water coolant FLOW problem, owing to the fact that the engine was still overheating with the thermostat jammed open. I would think that is the Specialists have not carried out this procedure ,,, they need to have the radiator removed and tested, all associated hoses and pipes removed and examined for "breakdown/separation of the internal rubber causing obstruction"
the pump unit flow and pressure rate should also be tested, Sarah the reason for it mainly overheating going up hill is because of the extra load /revs on the engine and the cooling system cannot cope.

My apologies to the Specialists if these tests/examinations have been carried out.

Good Luck.