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Saracen coolant pump

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Ah well, looks like I've found another project to keep me away from the Saladin! Took the Saracen (RF) for a run and it boiled. The previous owner had similar problems and worked out that the pump wasn't working, so fitted an electric pump between the thermostat and inlet (top) radiator pipe. Had no problems with it but now the electric relay switch has failed (which is why it boiled) and while I can replace that (having temporarily bypassed it) the electric pump is leaking anyway (not the connections, the pump body).

So, my first query is, how hard is it to take the mechanical pump off and fix or replace it - would I need to remove radiator to get at it or could it be done in situ? If it doesn't involve a huge amount of work I'd prefer this. Probably the best way to go in any event?

Second query is whether it would be reasonable to just replace the electric pump. However while it was working fine, it seems to be in a position where it is sucking water through the thermostat and back into the top radiator pipe rather than pushing it from the bottom radiator pipe into the gallery. So if I went down that path I'd be looking at connecting it to the lower radiator pipe, which might also be a pain.

Sorry to be so long-winded. Any advice appreciated!

James

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Decided to first see if thermostat was stuck closed, and discovered that it's been removed, so scratch one possibility. Removed the electric pump and will get tubing to see if the mechanical pump works (guess not but it was a NOS motor). Next flush the radiator and check the pressure valve, I guess, and then look for scarier things like head gaskets. Lots to do but think it's worth sorting out for the longer term.

My question at this stage is, do I really need the thermostat? Will it cause terrible problems if left out?

Thanks,

James.

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Hi James

I note your Saracen is an RF version. Does it have it have the sheet metal and rubber cowling over the radiator louvres on the front?

Another question, do the fans blow air out the front?

I ask these questions as have come across cooling issues before with RF Saracens.

regards Richard 

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Hi Richard

Been down the coast so nothing done today. It has the metal sheet and rubber cowling and I assume the fans blow out to the front but (hopefully tomorrow) I'll reconnect the output hose and run it into a bucket to see if the pump works and which way the wind blows. Will post again with those details. It seems that there are lots of possible causes so watch this space!

Cheers James

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1 hour ago, Aussie said:

Hi Richard

Been down the coast so nothing done today. It has the metal sheet and rubber cowling and I assume the fans blow out to the front but (hopefully tomorrow) I'll reconnect the output hose and run it into a bucket to see if the pump works and which way the wind blows. Will post again with those details. It seems that there are lots of possible causes so watch this space!

Cheers James

Hi James

OK, sometimes owners remove the cowling and then at road speed the hot air cannot get out, as yours is fitted another suggestion then. When you get the engine running, check that you have good airflow through the radiator. It is possible the the fins are blocked as oily residue and dust can be picked up from engine compartment, Ferret and Saladin suffered this as well.

regards Richard 

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Connected the outlet pipe from the thermostat housing (thermostat out) to a bucket, ran engine for 5 minutes and got 8 litres (2 gallons) of hot water (while running cold tap water with a hose into the filler hole). Running at only slightly fast idle. So about 0.4 gpm. Not sure what it should be but suspect at least 10 times that amount.

Air flowed out to the front (RF) and seemed reasonable. The engine bay is very clean so don't think the radiator fins are gummed up. However while it seems most likely to be the water pump I guess poor flow through blocked internal radiator tubes can't be completely excluded.

Need to decide whether to replace the mechanical water pump or fit an electric one to the bottom hose (or both?). Either way seems to involve a lot of dismantling (EMERs anyone?). Might try squirting water under pressure to make sure the internal galleries are patent but it was OK with the electric pump before the relay failed. Oil level seemed quite normal.

I think my next step should be to double check that water flow through the radiator is OK, and if I undo the drain plug and pour water in the top that should give a rough idea? Otherwise......:(O.o

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OK.. Removed the radiator and it needs a bit of a service but not too bad. Connected the electric pump (which is leaking) to the bottom hose and got 5 litres out the top pipe in 30sec, which is probably correct for that pump, though a bit light on for the engine, probably. Then ran the engine with the same set up for a minute but nothing out the top, so it is the water pump that's shot. Can't find the flow rate expected with the mechanical pump and would be interested if anyone knows.

What to do now? If I remove the water pump it will be a saga and I don't know if or how it could be repaired. Seems logical to fit a (bigger) electric pump to the bottom hose, if it can be wedged in there, but has anyone done that? Davis Craig recommends a 150 l/min pump +/- a digital controller to work the pump as needed for large engines, and this does look like the simplest solution...

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1 hour ago, Aussie said:

OK.. Removed the radiator and it needs a bit of a service but not too bad. Connected the electric pump (which is leaking) to the bottom hose and got 5 litres out the top pipe in 30sec, which is probably correct for that pump, though a bit light on for the engine, probably. Then ran the engine with the same set up for a minute but nothing out the top, so it is the water pump that's shot. Can't find the flow rate expected with the mechanical pump and would be interested if anyone knows.

What to do now? If I remove the water pump it will be a saga and I don't know if or how it could be repaired. Seems logical to fit a (bigger) electric pump to the bottom hose, if it can be wedged in there, but has anyone done that? Davis Craig recommends a 150 l/min pump +/- a digital controller to work the pump as needed for large engines, and this does look like the simplest solution...

Simple solution is to change the pump, they are available as are parts to repair it. Not that bad a job to remove rad and fans.

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Hi Aussie,

Sorry to have been a bit blunt in my last post. Whoever put that electric pump on the Saracen was not curing a problem. There is a possibility that the engine's water pump has had the impellor split (they are pressed on) and the parts could be obstructing the ports in the pump. The water flow in these engines is not like common engines, there are differences. Once the front armour is off, the rad can be removed leaving the fan assembly, and it will be a good exercise to make sure the fan belt adjusting pulleys are free to move, the sheaves are threaded.

regards, Richard

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Hi Richard

I just thought you were brief and to the point! I take your point that the pump might be blocking something and will take it out, although I might need a bit of hand-holding with this. I've sourced a NOS pump.

The front armour and radiator are off. Do I need to remove the fan assembly or can the pump be removed without doing this? Will have a look tomorrow to see where (what) the belt adjusting pulleys are. No idea what the sheaves are but might be obvious when I look.  Sorry but this process might involve more cries for help. 

Cheers

James

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That has to be the weirdest way to adjust fan belts! The Saladin has a jockey pulley and it's obvious how that works, however it's not clear how spinning the Saracen pulleys (sheaves - thanks Lowfat) to the rear along their threads loosens the belts - I can only assume that the fan axles are not parallel? Anyway, it does and I've got the belts off ( I hear your applause and a few groans).

5a6b1b8ddf8de_Saracen4.thumb.jpg.92e67b1254c8d5edfabea9bcf9bec9c3.jpg

My next dumb question: how do you remove the fan assembly? There are two bolts at either side and at the bottom there seem to be just a couple of pins, so it should just lift off. However there is stuff (mainly electrical connectors) in the way. I guess I have to remove those (not in the EMERs) but wonder if the bolts can be pulled down so the assembly could then swivel out rather than lifting it  up. The bolts might be fused to the rubber mounts so don't want to apply brute force needlessly.

5a6b17c2e373d_Saracen3.thumb.jpg.37c94810e795c0b8a1f31c28c04ceb21.jpg

5a6b1793f08d0_Saracen1.thumb.jpg.3125c9437490a7ecbbb2204172263f29.jpg

5a6b17b425ac9_Saracen2.thumb.jpg.64dd08ead895ab93d6e87587319166fa.jpg

Forecast 33C tomorrow and 39C Sunday so will probably give the shed a miss for a couple of days, but looking forward  to getting the pump out and seeing what's going on!

Cheers

James

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Hi James,

Those adjustable width pulleys are not that unusual, they are used where both drive and driven pulleys are on fixed points and a separate tensioner pulley cannot be fitted. They work well on the Saracen except when some heavy handed brute has over tightened the locking screws (the lock-wired ones) and distorted the thread in the pulley sheave.

cheers Richard

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Still a dilemma! Got the pump off and took the back off it but really can't see anything wrong. The impeller is in place and it spins without making any noise. No broken bits to see. (Also worked out how the adjustable pulleys work, once the belts were off - they are threaded together independently of the threads on the shaft, which are used just to line up the belts and pulleys).

5a6c550051227_Saracen5.thumb.jpg.3676726fb1ec5eabf737d6cbe6e8507f.jpg

 

5a6c550d4c582_Saracen6.thumb.jpg.1cd3262da78ed18fe4c5a3f471189ad1.jpg

 

5a6c551b1458e_Saracen7.thumb.jpg.9fcdd8256704af9d471ace81fbdffbf4.jpg

 

Now I'm really stuck! I'll replace the back on the pump and see if I can test it off the engine by spinning it e.g. with an electric drill. If it pumps then maybe the internal waterways are blocked, however water pumped through with the electric pump and it was a NOS engine so this seems unlikely. 

Back to thinking about an electric pump. I could replace the mechanical one but can't see how this will make any difference..

Sage advice please!

 

 

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If someone changed the engine, maybe the previous engine suffered from overheating. I would be looking at having the radiator checked by a specialist to see if it is restricted. Putting a hosepipe up it is not a guaranteed test that all the tubes are clear. Also now you are at this point is to flush out the cyl block waterways. There is no reason to fit an electric pump if the original pump is OK. Taking the thermostat out (I think you said it was missing), would allow the water to pass through the system too quickly and not have time to cool properly. I know of people who have done this on engines and ended up putting a restrictor plate in to slow the coolant. These vehicles operated around the world in all climates so there has to be a simple answer to your problem.

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Makes you wonder if there is something in the block restricting the water flow. I once had a problem with a V8 Cummins and got a woolly jumper out of the header tank, No one owned up to having one missing.

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Thanks guys

I've sent the radiator off for checking and have ordered a new pump and thermostat, so we'll see how it goes. Will also flush the block.

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On 12 January 2018 at 7:33 AM, Aussie said:

Decided to first see if thermostat was stuck closed, and discovered that it's been removed, so scratch one possibility. Removed the electric pump and will get tubing to see if the mechanical pump works (guess not but it was a NOS motor). Next flush the radiator and check the pressure valve, I guess, and then look for scarier things like head gaskets. Lots to do but think it's worth sorting out for the longer term.

My question at this stage is, do I really need the thermostat? Will it cause terrible problems if left out?

Thanks,

James.

I won't pretend to be an expert on the subject but, having recently sorted a B80 engine that was boiling up, I'll add my thoughts. 

The Rolls-Royce manual for the B80 states that it is OK to run without a thermostat but in that case the bypass port must be blanked off (the bypass is the smaller pipe that comes out underneath the thermostat housing).

The thermostat has a clever arrangement whereby when the thermostat closes, the bypass port opens and vice versa. My knowledge of this isn't complete (Richard's yer man for that) but my understanding is that the coolant won't circulate properly if the thermostat and the bypass are open simultaneously.

Upon investigation, I found that our B80 had been running without a thermostat and with the bypass open. This wasn't the only problem (the radiator had seen better days) but fitting a thermostat made a big difference.

I don't know whether your engine is a B80 or B81 but as far as I can tell the thermostat arrangements are the same.

I hope this is helpful.

Andy

 

Edited by mtskull

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Posted (edited)

Thanks Andy. 

As you said, the thermostat housing has a bypass that is open when the thermostat is closed, and closed when thermo is open.  Ist schematic scribble shows thermostat closed. The hatched "plugs are connected so when one moves the other does as well. With the thermostat closed, water recirculates through the engine block back to the pump and then back to the engine, with the radiator outlet blocked off.

5abd9e21b0292_Therm1.thumb.jpg.a15eded88b962e6f6e95ac4c0c4cdc3c.jpg

When the thermostat opens (rises) it pulls up the bottom plug and blocks off the bypass, so water goes from pump to engine then out to radiator and back to pump.

5abd9e3f667b2_Therm2.thumb.jpg.52457e9eb833ca378b21de904f6d0dce.jpg

All very logical, and with thermostat missing some of the water (possibly most, since the pump sucks it through the bypass) was recirculating and not going through the radiator. Maybe this is all that was wrong (bugger if it is, since there are now bits and pieces all over the floor that I have to put back on!). Certainly couldn't see anything wrong with the old pump (but have replaced it anyway).

So.. put a new thermostat in, and after the engine heated up and thermo opened, I got a flow of 4 litres (1 gallon)  through the outflow in 1 minute. Would hopefully be more if the engine was hotter and the thermostat fully open but at the moment I've just connected the bottom hose of the radiator and running the outflow into a bucket to measure, with a cold water hose into the top of the rad.

So........ as Richard advised that pushing water through too fast with an electric pump (Craig Davis recommends 150l/min) might not allow enough cooling time in the radiator, I'll put it back together and see what happens, although I'm still a bit concerned that the flow wasn't higher.

Cheers

James

 

Edited by Aussie
typos

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Ah well... hope this is the end of the saga!

On a whim I decided to replace the hose from the bottom of the radiator. Didn't look bad and I was in two minds because it's awkward getting the hose clamps off, but thought I might as well. Pulled the hose of and this dropped out of the hose:

5ac9b56d0aac1_Saracenplug.thumb.jpg.aa1bbffe7561703eb0f97af826cda8c2.jpg

A metal disc that is almost exactly the size of the hose! Which neatly explains why there was no water circulating from the radiator (not helped by the absence of the thermostat). I have absolutely no idea what it is (unfortunately doesn't seem to be a valuable roman coin) or how it came to be in the hose, and find it hard to see how any water got past it at all. Anyway,  I'm more confident than ever that there was nothing wrong with the water pump (that was replaced anyway).

Put it back together and ran it it for 20 minutes, with no signs of overheating and nice gradient of temp from top to bottom of the radiator. Measured around 85C at the thermostat housing, although the gauge on the instrument panel reads around 200F, so not sure that is all that reliable. Anyway, I'll take it out for a bit of a run when I get a chance, and am quietly confident that it's job done! (Apart from replacing all the armour, of course!)

Take home message: before dismantling armour plate, radiator/shroud, water pump, etc, first check the thermostat and next perhaps don't assume that your hoses aren't blocked!

Cheers, James

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2 hours ago, Aussie said:

 

A metal disc that is almost exactly the size of the hose! Which neatly explains why there was no water circulating from the radiator (not helped by the absence of the thermostat). I have absolutely no idea what it is (unfortunately doesn't seem to be a valuable roman coin) or how it came to be in the hose, and find it hard to see how any water got past it at all. Anyway,  I'm more confident than ever that there was nothing wrong with the water pump (that was replaced anyway).

 

Hi James,

I fitted a lot of Rolls reconditioned engines whilst working for the army and recall when they were preserved and packed that a metal disc was put over the water outlets and retained by  adhesive tape. Maybe someone forgot to remove it on fitting the engine.

regards, Richard

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I too have seen this, [plastic bungs left in a brand new pump

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How did you get on? I've given my Mk 5 Saracen quite a thrashing on hot days (45 Celsius) and the only thing that overheated was me.

 

Cheers,

Terry

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Was interesting and very nearly did my head in! Wasn't going to bore people with the gory details but since you asked...

Put it all back together and started it up in the shed; ran for around 20 min without any dramas so thought "job done". Then started it the next day to take it out and it played up royally - wouldn't start then ran very lumpily with smoke pouring out the exhaust and gradually died. So assumed the worst (head gasket) and considered taking it down to the valley for burial. Really couldn't face mucking around with it anymore, so got a friend (mechanic) to see if he was interested. Started it up for him - same performance but he said it was acting as if the choke was on. Assured him it wasn't but pulled it in and out so he could check the carbie end of the cable and... the sheath clamp was loose so pulling the knob in/out had no effect! He flicked the choke off and hallelujah! it immediately went back to running smoothly and sweetly. So after a week of foul temper I also went back to running smoothly. (Tightened the nut for the cable, of course - fiddly bit to get at).

What a saga! But fortunately this time the gods were just teasing me. Haven't taken it out on the road yet because I detoured to the dark side and picked up a HMMWV which I've just got on club plates today. Very tempted to swap a Cummins BT and Allison transmission into it to get the tyres smokin' but SWMBO reckons I should pull my head in.

Cheers James

 

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