Cylinder heads / water pump

[Malcstag]

Hi, Apologies but I haven't taken a Stag engine apart before...

After fitting a fully rebuilt engine I boughtthat had been stood for 5 years, although the engine was from a reputable supplier, I had an overheating problem in less than 100 miles of service (after torquing the head down three times).,( I saw a blast of steam exit the exhaust as I coasted the car in to the roadside) I was told the cause may be the water pump,as the car overheated so quickly on a 5 mile jouney unfortunately I have sheered the head off the bolt holding the pump impeller in! (it was a left hand thread), any ideas how I can get the pump out? Maybe it was ok anyway, it spins freely andfeels OK, I see from an engine diagram it meshes with a skew gear ona timing chain pulleybut surely it would spin when I turned the engine over with the cover off, it didn't though, is this correct?

I tested the thermostat and its fine, it looks new.

Luckily I got the studs offLeft Hand head easily (using two nuts method), I was shocked how corroded the stud threads werein the block, when I reassemble should I apply a barrier grease, say copper or graphite to assist the next person (maybe me again ) taking the studs out?

I pressure tested the pots (cold) before starting the work, they were all 125-145 lb, except two that were 105lb. I imagine these were the two that blew unfortunately one on each head. I notice on the left bank the 1st pot (nearest the bulkhead) is extremely close to a water way, is this a weak point? I cant see the gasket breach anywhere as the engine wasn't run long enough.

I haven't taken the right hand off yet.

Appreciate any advice as I am stuck with doing the work on my own.

[alan_thomas]

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Malcstag wrote:

it spins freely andfeels OK, I see from an engine diagram it meshes with a skew gear ona timing chain pulleybut surely it would spin when I turned the engine over with the cover off, it didn't though, is this correct?

Spins freely is bad! the water pump is, as you say, geared to the jackshaft. So it probably was not pumping water.

Under the impeller the pump cageis simply pushed in with a couple of 'O' rings to stop leakage. To get it out you would normally rotate the Bolt head and the bevel gear on the end cannot rotate the engine so it forces the pump cage out. This will not work in your case as the pump spins. The next way is tobackoff the L.H threaded bolt wrap a piece of welding rod or similiar a couple of times arount it then form a loop on the top. ( the idea is to make a hook anchored to the bolt) Then use a slide hammer to bang it out. I have done this without a slidehammer by making the loop about a foot long and then using an ordinary hammer to come up inside the loop and this forces the pump out.

You say you have sheared the bolt in this case you will have to either find some other way of pulling the impeller off ( its a press fit on the shaft) or drill a small hole down the centre of the sheared bolt andtap a threadin it, and fit a smaller bolt just to have something to pull against.

I am afraid the prognosis is not good there were a batch of replacement water pumps where the shaft was not hardened and the gear stripped off. Changing the water pump is not that difficult, removing all the debris when it is spread around the engine is hard. Also it rarely leaves the jackshaft in a usable condition.

Hope you get on OK, use the forum to vent your frustration or air your ideas

- Alan

[alan_thomas]

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Malc,

I thought you may be able to learn something from someone else in a similiar position see

http://192.94.170.51/start/phorum/re...9616#msg-19616

a thread on the 'other' stag forum, exactly the same problem as yourself. if you search the forum there was lots of discussion over this one.

- Alan

[DJT]

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Sorry to say it, but I have to agree with Alan. If the pump spins freely, then it has lost drive from the jackshaft. The thread Alan has linked to is mine. The sad tale is also described on here. See http://stagownersclub.mywowbb.com/forum1/227.html

The symptoms are identical to my experience.

Having sheared the bolt, you have a problem. I removed my pumpby slackening the bolt a bit and using a couple of pry-bars under the head to lever it out. The brass cage usually stays in place and has to be removed separately. Not easy, I am afraid and you will have to use a bit of initiative to make up a suitable puller.

In your case you may be successful removing the pump using Alan's suggestion.

When you get it out, you will almost certainly find that the pump has destroyed the jackshaft gear as well. So this will have to come out and be replaced, which involves removing the timing gear/chains. Then there is the worry about where the metal from the gears has gone. I was recommended to strip the engine completely and flush everything clean before rebuilding again. I replaced the jackshaft and rebuilt an old, known, pump. Drained the oil and refilled with a new filter. Ran the engine up to temperature, then drained oils and replaced filter again. I have a magnetic sump plug which collected some metal filings. Changed oil and filter yet again after 100 miles.

I followed this route because I knew the pump had been in situ for about 16 years and 50000 miles, so the wear had been gradual. There was also no sign of any teeth being sheared off, so I was of the opinion that there were no large bits floating around. So far, so good.

I am really sorry to be the bearer of bad news. I hope I am wrong with my diagnosis, but..............

There were a lot of poor quality water pumps around a few years ago, and I would suggest your engine was rebuilt with one. Whether you have any comeback against the supplier depends on how it was described when he sold it and what, if any, warranty he gave you. I would certainly go down this route before going much further with the dismantling.

Dave

[Malcstag]

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I feel sick.........

I will let you know how I get on.

Cheers guys.

[les M]

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Malc

If all else fails it is possible to remove the pump by ether making up a puller with hooked ends and using the vent holes in the impeller as locating points, or to tap threads into the vent holes and then use bolts to pull from.

Good luck

copperslip is very good for the cylinder head bolts and studs but make sure that the cylinder head holes are clear of corrosion, and try not to get any copperslip onto the mating faces

Les.

[DJT]

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les M wrote:

copperslip is very good for the cylinder head bolts and studs but make sure that the cylinder head holes are clear of corrosion, and try not to get any copperslip onto the mating faces

I can confirm this stuff is good for preventing corrosion on the studs and bolts, but make sure you keep the threads dry and clean. Copperslip will reduce the friction on the threads and this messes up the torque settings.

Dave

[Malcstag]

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Many thankd , i feel sick.

Its a shame taking all those new gaskets off and starting again, what a waste.

I hope some teeth are still left on that shaft when I shove it up the sellers xxxx!

this was a new pump supplied by a well known supplier, i'm gutted.

Back tosquare one and take the engine out , again... no holiday again this year.

[Malcstag]

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Right, I've calmed down....Just as well its raining.

I've taken the engine out again, after much research I have been told early 6 vane pump is better, the curved fin profile will force water round, 12 vane just thrashes it round, I see that the housing is less restricted on the 6 vane,and that will need changing too.

There are plenty of 6 vane rebuilt pumps out there in the US for about ÂŁ100 from early TR7s, and a lot of new 12 vane for TR7s but the source is unknown for these new ones with rumours of soft geared shafts out there. I have spoken to an engineer who had these shafts tested and was told technically they were fine, quite possibly they were not meshing correctly with the jackshaft, or seated correctly.

I wrote to a Saab owneras the 90/99 shares the same block as a TR7 and Stag (lh and top) regarding an electric pump fitment.

http://www.geocities.com/saab99ewp/EWPFAQ.html



this was his reply ..

Hi Malcolm!

Wow, a Stag, how cool. My first car was a ’65 TR-4, I drove that thing everywhere. Always liked the Stag, it was like a TR-series all grown up.

I got an email from a fellow with a Stag a couple of years ago asking the same question. My answer to him was that it should be possible, I cannot see why not. I have received emails from people who have converted all sorts of cars to an EWP.

The way I did it was to “map” the entire cooling system on paper and figure out how everything flowed. Once I had that figured out, I designed the plumbing. I went through 2 or 3 versions before I settled on the final version. There are a couple of things to keep in mind:

The pump should be as low as possible in the system. At a minimum, it needs to be below the highest point of the system (which should be the stock bleed nipple). But really it should be down low in the engine compartment. The pump will not have to work as hard this way. The pump needs to always be immersed in coolant while it is running. So keeping it low will also ensure that an air pocket does not form near the pump and damage it.

Flow rates. I am not an engineer and this is where I ran into problems. Specifically, with the heater core. You need to match the size of the stock plumbing as close as possible. Coolant will flow in the path of “least resistance” so if the path to the heater core is smaller than the path to the engine… no heat. There is a heater valve somewhere on your car that you will have to figure into your design. One flow for when the valve is open, another for when it is closed.

“Stripped gears” oh brother have I been there. BTW, my 99T is still running the EWP and it still works perfectly after some 4 years on the road. Good luck!

- Mark

Everett, WA

I just love his comment bout the Stag being a grown up Tr! yes!

Meanwhile, I have found a well known retired engine builder who will take my engine apart, clean it out a fit a matched pair of rebuilt pump and shaft to stop this happening again. I hope to be at the National Weekend yet!

[Malcstag]

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OK, my engine is rebuilt! New 6 vane pump & cover and matching jack shaft.

The fault lay with the water pump housing, it wasn't shimmed properly with enough gaskets and was pressed down onto the impeller, the friction was enormous, enough to strip the teeth of the pump & jackshaft. The engine was originally built by Newark engines, I gather they are out of buisness now, good!

You can testfor problemsby rotating the jackshaft by hand (before fitting the timing chains) , any large force would indicate friction with the pumps gear or impeller. The old pump was removed by welding a nut to the shaft, difficult as the heat was being transferred quickly, smashing the impeller off helped.

WARNING : Another fault was the use of new cylinder head studs, they were worse than crap, I clamped one in a vice and torqued it up and you could keep going basically, make sure studs are hi tensile steel, not mild steel as supplied new by the main suppliers, you are better off with your old studs.

I'm pleased its still raining, I can get on and fit the engine now.

[TimShoubridge]

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Malcolm,

Glad to hear all is ok now and that you have not missed too much driving with this weather.

I know that many organisations can have the same name, but a NEWARK ENGINES has become a big seller on fleabay, knocking out engines and cyinder heads etc. May be a totally different company but beware.

Tim