sudden overheating - early water pump

[CovKid]

He won't be your friend anymore if he gets a bolt or two like I did

[waltraud]

Cov- after doing this job on mine the fan came on later than expected, perhaps due to temp gauge and effectively the whole system working as it should for the first time in some years. Relieved eh!

[CovKid]

Aye, its just a bit nerve-wracking wondering if it will or not. It could be that theres still some air in system and as a result, even though water in engine bay is hot, rad still isn't getting hot enough to trigger switch. Certainly without my intervening, leaving it parked and running, the temp guage goes way higher than I'd feel comfortable with and fan doesn't kick in on its own. You're right though, I may just need to let the system settle, bleed again, and see if it comes on. Just glad I have an overide.

I think there was some discussion a while back as to whether fitting a manual chicken switch for the fan was worth it or not. After all, a normally functioning cooling system shouldn't need one but in this instance its saving my bacon.

Since the overheat I've had niggling probs with ancileries that don't quite function as they should - could be that the high temperatures involved (or clouds of steam) have affected some parts. Time will tell.

The other thing I've noticed is that much of my main charging circuit cables are well past their best with no shiney copper even if you cut the wire back. I suppose the best thing to do is fit new stuff - much of it is original by the look of it. I gather that if these cables aren't sealed properly at each end with shrink tubing, the corrosion can work its way up the cable beneath the protective coating.

[Steve T]

CovKid
I had issues with air when I replaced my water pump, 2 day job from start to finish, similar issues as you! With the same seized bolt.

The only way I could get rid of the air was to ease the main hose off the block with the bleed valve holding the 4 main water pipes in the engine bay, that let a lot of air out and sorted the air lock out.

Lot of air gone and a lot of water to replace it, perhaps it is worth a go at that to eliminite any air there, but you say you can't bleed at the rad? Or did you get that sorted.

Interesting read and wiki write up by the way

Regards Steve

[pionte]

Just reading your post brought it all back to me ... when I did mine last year, the thermostat housing and water pump had become one.. it was a bloody nightmare, in the end I had to drill the bolts out and repair the damaged thermostat housing . As you probably know , these metal thermostat housings are rarer than hens teeth ( it has taken me almost a year to finally source another good one as a spare ) It certainly wasnt the 45 minute job that I was expecting to replace the stuck thermostat !

Good tip about replacing the hoses, I used silicon replacements .

And also your point about getting the air out of the system, best to give it some revs and get the water really flowing around the system, I followed Simon Baxters advice on how to bleed and it worked perfectly.

glad you have it sorted,

[CovKid]

I found I needed to get it up to 2500 revs before the water was pushed to the front. I'm getting water there now but fairly sure theres still air in the system. Come to think of it, I had probs leading up to this with overheating in heavy traffic and having to use the chicken switch sometimes, so perhaps water had been seeping from the pump over time and introducing air to the system. Both tanks would have checked out ok but a pocket of air at top of rad would have reduced cooling effect and cause overheating in traffic. Kinda makes sense now.

I won't forget the trauma of those bolts in a hurry though....

The one good thing (apart from being mobile again) is that because all that lot has been off and dodgy bolts replaced with new, it'll be a easier to get off again should the need arise and virtually a mornings work rather than 9 days...

For anyone else who hasn't overhauled the pump/thermost, expect the worst and if the vehicle is off the road for a long period of time, it might be a prudent time to get it all off and renew accodingly. When they blow, they blow.

I'll add extra comments on specific issues with bleeding to that WIKI piece to save anyone else hassle.

[CJH]

I'm now dreading this. When I bought the van I naively bought a new thermostat as part of a planned basic first service, but when I saw what was involved I put it in my box of spares. It's still there. I'm wondering now if I should pick up a replacement thermostat housing when I see one and keep the thermostat/housing/pump combo as a ready-to-go exchange unit.

But I wonder, how different is the early system from the later one? If someone is changing the water pump is it feasible to convert to the newer pump and thermostat at the same time, albeit with a bit of modification to the pipework?

[Steve T]

Agree with the revs, they need to be high, ideally a spare pair of hands to assist. Also worth noting mine does run cooler since pump replacement, only a few degrees but poss goes to show the pump was not as efficient as it should have been. I just had a drip from mine, changed it when it started squealing, but play on pump was evident before this. The Baxter bleed method is the guide I used.

CovKid, I wonder if yours got that hot that it may have dislodged some crud in the system and blocked the small orifice on one of the small pipe connectors in the engine bay, can't remember correct one but it is one I manufactured a while ago to replace a broken one (on one of my posts)

[pionte]

I'm now dreading this. I'm wondering now if I should pick up a replacement thermostat housing when I see one and keep the thermostat/housing/pump combo as a ready-to-go exchange unit.
?

thats a great idea, my van was off the road for weeks whilst I sorted the original thermostat housing out, start looking now ! seriously these are hard to find.
Far better to tackle this job when you have all the parts lined up ready to go, and maybe in winter time when you wont be wanting to use the van rather than the night before your annual holiday .. If you are lucky and your old thermostat housing is still usable then you can re sell it .

[CovKid]

I think its worth converting to the more common set up but could be a nightmare in terms of hoses and stuff. I don't know anyone who has done it. I presume its possible unless the engine block is vastly different.

[waltraud]

My advice is to prep as much as possible and in my case a week of plusgas soaking in all necessary areas meant that thd job was more straightforward.....of course it might be luck or the housing had been removed not so long ago etc......the parts really are getting rare and if you find one at a fair price I would get it!

[CovKid]

Or print one. Won't be long before that will be dooable....

Go away for a week and print a whole T25.

Not so sure about doing a pump swap during winter months. It was bad enough in fair weather but numb fingers plus stuck bolts has to be the pits.

[CovKid]

52 mile run today today up the A5 (Tamworth and back), varying speeds (up to 70mph) and sitting in traffic at times. Temperature ranged from cold to moderately warm but not remotely hot.

Arrived in Tamworth first thing, engine at what I'd consider was 'normal' and managed to expel a little more air via rad in the car park. Worked there all day then tootled home and temperature seemed even more stable. Never really got hot enough for the fan to kick in. Think I'll replace the fan switch to be on safe side.

The new thermostat that I was convinced was faulty, probably wasn't then, (probs wholly down to not bleeding properly) so I'll test it, refit it when I get chance, and that should improve the initial warm up.

I've never checked/reset the tappets in 8 years (never felt it needed it) but I'll do those at the weekend and give it a good service. Everything may be back to normal then.

[CovKid]

Just an update (post-overheat).

I discovered that the elevated temperatures took out radiator fan switch (since replaced) and the expansion bottle had clear evidence of stretch marks. Replaced with new clean bottle from GSF that even came with dalek cap (£20 all-in I think). Quacked like a good un whereas old one's valve had clearly gone. Didn't lose much water swapping bottle - few squeezes of the hoses after removed any air.

Temperature now returned to stable at last (just past LED), even sitting in nose-to-tail traffic today so that part is sorted now. Slight misfire at idle though. Perhaps new plugs and a tappet check will help with that - if not at least it runs and there seems no loss in power whatsoever.

I think I got off lightly considering it maxed out on temperature and the absolutely horrendous problems I had getting the old pump off and that thermostat bolt shifted....

[pionte]

Glad that it is looking like being sorted... just in time for all the HOT weather we are going to have