Bongo Towing

[mikeonb4c]

Well I am not going to disconnect the cooler to find out! I doubt it will have made much difference as there wasn't much sludge that came out of the old rad but who knows?

All I know from 30+ years of experience with rebuilding auto's is that towing puts a huge amount of extra load on the torque converter & that is where most of the heat is generated in a transmission. More heat = more cooling needed. Simple.

All I am trying to do here is give people sensible informed advice, that is also cheap insurance as far as the transmission goes, doesn't make any difference to me if I am ignored & transmissions carry on getting fried.

I've enjoyed reading your knowledgeable posts - very informative and thanks v. much. My Bongo does fairly light duties generally but its still got me thinking

[missfixit70]

I was just looking for a few answers, sorry if I offended by asking questions (isn't that what a forum is about? Questions, discussion & debate?), certainly not ignoring you, or questioning your years of experience. I have an enquiring mind & a pretty good understanding of what's going on, admittedly I don't have a huge knowledge of autoboxes, but it's still a piece of machinery that needs to get to a certain temperature & then that temperature has to be maintained via a cooler.
One more question from your description of how you fitted yours, it sounds like the original cooler is still connected (ie in parallel) as you describe removing it from the system as an option if you suspect it's integrity.

[Alacrity]

Sorry was a bit grumpy last night

Yes my rad cooler is still in the system, you would only want to pipe it out if you suspected it of leaking - not something I have heard of on Bongo's but theoretically possible. I have vehicles in here for a trans rebuild where the cooler has filled the trans up with coolant & the cost of a replacement rad is serious money (Chysler Voyager for example), so if the customer doesn't want the expense (on top of a box rebuild) then a much cheaper option is to pipe out & seal off the rad cooler & just run on thenew one. They tend to be more efficient anyway as they are air to oil as opposed to hot water/oil.

[helen&tony]

Hi Alacrity
I'm enjoying this thread...I could regale you with tales of our epic journey here, towing a caravan, and how I concluded that the frequent need for stopping along route, and dreadful slow progress was due to transmission heating...2 hour stops, and performance back again...I had always intended to fit a cooler/ stat, but it's on THAT list ...Next question from me is where to get a small external cooler....I rather fancy a Serck or similar, and ducted air from behind the front wheel somewhere, to a cooler mounted in the area under the drivers seat...Feasible, or must it sit in the front somewhere?
Cheers
Helen

[Alacrity]

Personally I believe the best (& easiest) place to fit the cooler is up front as shown in my pictures, that way the kits we use fit straight on with no detrimental effects to anything - here in the UK at least. If you are fitting one elsewhere you may well need one with its own stat controlled fan but then you have to fabricate brackets & will be, in general, pulling much warmer air through the cooler which will not be as efficient. Also be aware that coolers mounted under the vehicle - such as in the area of the rear heater gubbins as suggested earlier, will be vunerable to being clobbered by stones thrown up by the front wheels.

[helen&tony]

Hi Geoff
MMmm...kits...sounds interesting..I like ease of finding...are they expensive with a stat?
Cheers
Helen

[missfixit70]

Personally I believe the best (& easiest) place to fit the cooler is up front as shown in my pictures, that way the kits we use fit straight on with no detrimental effects to anything - here in the UK at least. If you are fitting one elsewhere you may well need one with its own stat controlled fan but then you have to fabricate brackets & will be, in general, pulling much warmer air through the cooler which will not be as efficient. Also be aware that coolers mounted under the vehicle - such as in the area of the rear heater gubbins as suggested earlier, will be vunerable to being clobbered by stones thrown up by the front wheels.

You misunderstood me I am removing the rear heater to utilise the space for water tanks etc (which is internal anyway, so would be no good as a position for an external oil cooler) & was questioning the possibility of using the matrix (mounted in a similar postion to yours) as an oil cooler.
If you connect the cooler as you have done in parallel, then surely some of the oil will be going through the original cooler, which if it is indeed not doing much, kind of negates the effect of fitting an extra cooler to some degree. To me it would make more sense to cut the original cooler out of the loop completely if you need extra cooling, surely that way you wouldn't need as big an external cooler to do the same job?

[Alacrity]

Ah I see, yes, sorry I didn't read it right. Not sure if a heater matrix would stand the pressure? I know the oil coolers circuit on this particular transmission probably only runs up to about 30psi (& that is an educated guess as that is what they normally are) I am not sure what the heater matrix designed pressure is? If it will stand the pressure then there is no reason to suppose it won't work. I don't think I would risk it though in case it blew out on me - it also may have crud in it that may not be easy to remove & could end up in the cooler lines (see bit below about restrictions). I know the additional cooler I use will stand pressures up to 300psi as we use them on some trannys on which the cooler circuit is running at main line pressure, which can vary between 75 & 300 psi. Be carefull if not using a deignated trans cooler as it is critical that cooler flow is not restricted, not only will this cause the trans temp to rise but, as the trans uses the cooler return oil for pressure lubrication (as per a crankshaft in the engine) of the bushes & bearings, you could end up destroying the transmission geartrain. Seen that done a few times where some smart arse has just blocked off the cooler telling the poor owner "they don't really need it"

Most original coolers will, unless totally buried in silt, be doing some cooling (in my case I have just fitted a new rad so it should be as good as new) so it is as well to leave it in the line. It could be argued it will help trans warm up but I think it more likely the trans will help engine warm up, these things warm up very fast - especially when the striving from cold is stop/start (converter doing a lot of work = heat). The extra one is fitted in series not parrallel so all the oil still flows through both coolers.

I did look at mounting a remote cooler with fan & stat under the car but (apart from making a lot more work) I couldn't see anywhere where I would be happy that it wouldn't get shrapnel thrown at it. Bear in mind the stat on the fan type only controls the fan operation not the cooler flow.

[missfixit70]

That makes more sense that it's in series, was misunderstanding your fitting description
I'm glad you mentioned the possible heating effects of the internal cooler, it's something I've wondered about, ie is there an initial warm up heating effect & which way does that heating effect work? I don't think there'd be much effect either way TBH due to the fact the stat isn't open at those low temps so no flow through the bottom part of the rad, so there is no flow across the internal cooler.

[helen&tony]

Hi Alacrity
The heater matrix is rated for coolant at 1.1 bar...I don't know how Mazda Japan rate pressures according to industry working standards, but in the UK it's normal to rate something up to 2 1/2 to 3 times working pressure. Whether this applies to the auto industry, I doubt it...so it would be rated around half what you say the oil system would need.
Cheers
Helen

[missfixit70]

I was just going to go & work out relevant pressures, saved me a job Helen, I suspected it would be a no go

[Alacrity]

is there an initial warm up heating effect & which way does that heating effect work? I don't think there'd be much effect either way

I agree, I would think it isn't even worth considering to be honest.