Aragorn Posted June 21, 2009 Share Posted June 21, 2009 Ok so i've baught myself an old disco V8 with the idea being to make it a cheap and cheerful offroader for the summer, as the defender is taking forever and soaking up too much cash to be finished any time soon! I've been sorting bits and bobs for its MOT, and bar 1 rear trailing arm bush and fixing the clutch its ready to go, barring any engine issues. So the engine itself is a 3.5L V8 with two carbs on it. It starts, runs and idles nicely. When i baught it they guy told me the water pump was leaking and needed changing. This wasnt evident when we started it in his yard, so i hoped i'd get away with it, but it seems from running the motor today that it is infact leaking. The block area below the pump was wet after moving it this morning to do the welding it needed. So i need to change the pump it seems. However when looking it over i noticed somthing odd. The engine had been run for perhaps 3 or 4 minutes from cold, when moving it from the parking bays to the garage to do the welding, most of that time was idling, as i was fighting with the clutch. I popped open the expansion cap to see if it had used much water, and i was greeted with a nice gueyser style eruption from the tank. There wasnt that much that came out, but it still erupted, which seemed strange to me. So i left the cap off and fired it the engine up to see what would happen. I could rev it up to say 2-3krpm with nothing much happen in the headertank, but as soon as i lifted off the throttle, i got the guyser effect again. So any ideas on that? I had to change the heater matrix, as it had split (presumably frost damage), i'm just a bit worried that the engine itself has suffered the same fate... The next issue with the motor is that i took it a run up the farm track after finishing the welding, and noticed that it didnt really like wide throttle angles. It just seemed to bog down and stutter. I pulled up and tried to rev it in neutral, and it managed to get to about 4krpm, before starting to missfire. No amount of extra throttle would raise the revs any more, it just missfired more. Is this likely to be a problem with the ignition system? Could it be related to the above problem? Hopefully someone can give me some pointers. Cheers Kev Quote Link to comment Share on other sites More sharing options...
Boothy Posted June 21, 2009 Share Posted June 21, 2009 A couple of questions really, Does it smoke, and if it does is it white steamy or thick oily ?? What is the oil like when you remove the dipstick tube, I hope not but is it yellowy custardy ?? Missfire could be caused by water wetting thedizzy cap and leads hopefully. It doesn't sound good to me I'm afraid, it sounds very much like its pressurising from a craked block/liner or head gasket or perhaps hopefully its just the pump or valley gasket or something, sorry but I fear the worst. Quote Link to comment Share on other sites More sharing options...
Aragorn Posted June 21, 2009 Author Share Posted June 21, 2009 Theres nothing from the tailpipe at all by way of smoke. Oil looks oily, perhaps in need of change but not emulsified last time i looked anyway. I'll check the oil again just to ensure its not changed since i've been running it, but it will be next weekend before i can get a look at it most likely. Whats the Valley gasket? and why would the pump gasket cause these symptoms? Cheers Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted June 22, 2009 Share Posted June 22, 2009 A word of caution - If you just run it for short periods it will get emulsion in the breathers and possibly filler cap anyway as natural condensation mixes with the oil but doesn't get a chance to burn off, the 109 used to do that when I used it for short journeys yet there was nothing wrong with the engine. Quote Link to comment Share on other sites More sharing options...
Quagmire Posted June 22, 2009 Share Posted June 22, 2009 Whats the Valley gasket? and why would the pump gasket cause these symptoms?Cheers Valley gasket is the gasket on top of the engine, between the inlet manifold and block. I think Boothy is saying you might have a leak on one of the waterways there, the book advises you smear a little blue hylomar on the gasket around the ports for the waterways when fitting (if you change it). As Boothy said, if the dizzy or leads are wet then you might get a misfire, otherwise it sounds like timing? Is the missing always at the same spot? Could be an issue with vac or mechanical advance not working i guess. I'd concentrate on the water situation first though. One more thing- surely if its a 3.5 on carbs then we aren't really looking at a liner/block issue. If it is anything like that it'd be a gasket surely? Quote Link to comment Share on other sites More sharing options...
Hybrid_From_Hell Posted June 22, 2009 Share Posted June 22, 2009 When i baught it they guy told me the water pump was leaking and needed changing. This wasnt evident when we started it in his yard, so i hoped i'd get away with it, but it seems from running the motor today that it is infact leaking. The block area below the pump was wet after moving it this morning to do the welding it needed. This is prob coming from the hlole below the seal bearing area, and if leaking yep, needs changing However when looking it over i noticed somthing odd. The engine had been run for perhaps 3 or 4 minutes from cold, when moving it from the parking bays to the garage to do the welding, most of that time was idling, as i was fighting with the clutch. I popped open the expansion cap to see if it had used much water, and i was greeted with a nice gueyser style eruption from the tank. There wasnt that much that came out, but it still erupted, which seemed strange to me.So i left the cap off and fired it the engine up to see what would happen. I could rev it up to say 2-3krpm with nothing much happen in the headertank, but as soon as i lifted off the throttle, i got the guyser effect again. So any ideas on that? I had to change the heater matrix, as it had split (presumably frost damage), i'm just a bit worried that the engine itself has suffered the same fate... Several things Its 1st a bad idea to do what you have done, as Rog IStruggletogate11 showed in his recent post, but you prob know that already do, the things it could be are Air lock (you have changed the matrix ? Head gasket(s) gone Valley gasket leaking The water level will drop / would have dropped due to your water pump leak, V8 and RR particaularly can give issues with air locks and be a right royal PITFA to get out but the 3.5 block is not a block that liner or porus issues arise within, the 4.6s etc tend to make people think anything water related on a V8 is the block gone If you can get the gasses in the exp tank checked for leakage ie heads etc, and at the same time pressure test the system, again prob point to heads, you can get some dye indicator stuff that will show a visible leak, but I think this is prob heads - ie if the water pump has been leaking then ater level will have dropped if he ran it like this then it would easily then overheat with low collant and that = heads 99% of the time The next issue with the motor is that i took it a run up the farm track after finishing the welding, and noticed that it didnt really like wide throttle angles. It just seemed to bog down and stutter. I pulled up and tried to rev it in neutral, and it managed to get to about 4krpm, before starting to missfire. No amount of extra throttle would raise the revs any more, it just missfired more. Is this likely to be a problem with the ignition system? Could it be related to the above problem? Hmmm. Someone who couldn't / didn't sort the water pump has prob not exactly thrilled it with presents of service bits Try new plugs (NGKs) new air filter, and check the dizzy cap / rotor arm - 1st to see if genuine (if not bin and replace with genuine only - 2nd to see if nasty - if so replace, what are the leads ? cheapo ones cause all sorts of issues, replace again for my money genuines are good value and fit properly, and then check the timing and dizzy is advancing properly, check oil in dashpots and generally give it a good service before worrying too much HTH Nige Quote Link to comment Share on other sites More sharing options...
Aragorn Posted June 22, 2009 Author Share Posted June 22, 2009 Cheers for the advice. As you can imagine i dont really fancy throwing tonnes of cash at the engine until i can be sure its not knackered. My worry is that the heater matrix had split right down the plastic end tank, which to me suggests possible frost damage, especially if its been using water and topped up a lot, then left sitting over winter... I wouldnt have expected the geyser from the header tank on a cold engine, which is why i opened it without giving it much thaught, perhaps it just heats up quicker than i'd expect. A combination of an alloy block and it being a 3.5L V8 presumably means it will heat the water more quickly that an iron block I4. I think i'll change the water pump, and give it a run and see what happens. Is there a procedure to bleed these engines? The heater was blowing hot air after only a few minutes running, so that would at least suggest the matrix isnt airlocked, however all i did was fill the expansion tank and squeeze the hoses a bit. I realise now that there is a bleed screw on the top of the rad, which i didnt think to open, however the rad hoses were warm. What do you mean by "oil in dashpots"? Cheers Quote Link to comment Share on other sites More sharing options...
Aragorn Posted June 22, 2009 Author Share Posted June 22, 2009 Just a little update, i asked my mate to check the oil in the sump to see if it was emulsified further to someone asking above. The oil looks normal, however he said he removed the reservoir cap and the cooling system still appeared to be pressurised (i presume he got a gush of coolant again like i did when i opened it yesterday), even though its not been run since yesterday afternoon.... Quote Link to comment Share on other sites More sharing options...
Quagmire Posted June 22, 2009 Share Posted June 22, 2009 the cooling system still appeared to be pressurised Have you checked the plugs? Got any cleaner than others? That would indicate water in cylinder and potential head gasket failure... As for oil in the dashpots- if you unscrew the big black thing from the top of the SU's you will find you can pour oil in them, these are the dashpots that damp the motion of the piston and therefore the needle as it moves up and down. If one side is reacting different to the other you can get bad running. Do one carb at a time- do not mix the dampers up! I tend to take the top off the carb so that it I can get it spotless inside- you can also then sit down somewhere nice to clean them, like the kitchen Undo the three screws at the base of the carb "dome" bit. Lift it off. You will find a big (but weak) spring, and the piston that holds the needle assembly. you can take these out and clean them too if they are gunked up. Now with the top you removed, unscrew the black plastic screw thing at the top and withdraw the damper. Clean meticulously and put to one side. Now do the same with the "tube" that you removed it from. You will find that it is (probably) full of rank oil that is black. Once all clean, reassemble carb top onto body, replacing needle assembly and piston. The piston can only go in one way as there is a tab that locates in a notch in the carb base. Now you have a carb minus damper. Simply fill the top of the damper with ATF or 20/50 and replace damper, thicker oil will give more richness on acceleration. The oil should be filled to 13mm above the damper top when inserted. I always just guess mine and make sure each side is the same. Screw damper back in and test when both sides done. Quote Link to comment Share on other sites More sharing options...
Aragorn Posted June 22, 2009 Author Share Posted June 22, 2009 cheers for that, can get looking at the carb tweaking once i get it running and MOT'd Sounds a bit scary reading it there, but i guess once i've actually dismantled it it will be fine. I've not checked the plugs yet tbh, spent most of saturday hiding from the rain refitting the heaterbox and dash, and sunday wedged underneath it doing the welding. Might be a check work doing, but seen as theres no steam out the tailpipe its unlikely imo? Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted June 22, 2009 Share Posted June 22, 2009 I find the best way to adjust carbs is to slacken off all the bolts until they can be placed squarely in the bin, and then fit EFI. Quote Link to comment Share on other sites More sharing options...
Aragorn Posted June 22, 2009 Author Share Posted June 22, 2009 Oh i quite agree with you on that one, however this is a low cost project, so unless someone drops an EFI manifold, loom and afm on my doorstep for a fiver then it wont be happening! Quote Link to comment Share on other sites More sharing options...
Quagmire Posted June 22, 2009 Share Posted June 22, 2009 Sounds a bit scary reading it there, but i guess once i've actually dismantled it it will be fine. Its not really- SU's have hardly any moving parts I have a link to a decent manual - mods please remove if this breaks any rules... Weber/SU Manual I find the best way to adjust carbs is to slacken off all the bolts until they can be placed squarely in the bin, and then fit EFI. I have EFI stuff ready to go- honest! Have inlet manifold, injectors, plenum loom etc from old flapper system- just need to get the MS 'n' EDIS Allocated funds always seem to get trashed on other more 'important' things like gearboxes Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted June 22, 2009 Share Posted June 22, 2009 Oh i quite agree with you on that one, however this is a low cost project, so unless someone drops an EFI manifold, loom and afm on my doorstep for a fiver then it wont be happening! Double your budget and it's just about doable - find some luddite who wants to switch the other way and it can work out costing nothing. I don't usually pay more than £20 for a complete setup although I am never after the ECU or AFM I believe these days they're not the pricey items they once were. Quote Link to comment Share on other sites More sharing options...
Aragorn Posted June 23, 2009 Author Share Posted June 23, 2009 In that case i'll get it running and MOT'd then keep my eyes out for the bits. I just figured that most people breaking suitable vehicles would want to sell everything complete, meaning i'd have to spend silly money to get the parts required. Megasquirt would be nice, but again its cost, plus after an attempted mapping session years ago using a DTA ECU i'm not really sure i'd be up for trying again unless i had a map that was pretty close and i was just tweaking it to get it right, although saying that apparently the megasquirt is pretty easy to map. I'll maybe spend some time going thru the monster megasquirt thread at some point. I've ordered up the parts, and i'm going to change the water pump and clutch bits at the weekend then go from there. Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted June 23, 2009 Share Posted June 23, 2009 unless i had a map that was pretty close and i was just tweaking it to get it right, although saying that apparently the megasquirt is pretty easy to map. I don't wish to sound like I'm encouraging you, but yes it is easy to map and yes there are plenty of maps available on here that would get you pretty close. TBH I'm not sure it's worth converting a stock 3.5 to EFI when you could buy a complete vehicle as an MOT fail for half of nothing and take the engine & everything out complete - you'd save finding things like the HP fuel pump & tank. Aaaanyway, glad you've got it going. Quote Link to comment Share on other sites More sharing options...
Aragorn Posted June 23, 2009 Author Share Posted June 23, 2009 Its not going yet lol! Thing is, an MOT fail truck is going to be 2-300quid, which is quite a lot more than i'd be willing to spend on the EFI bits, and generally you need a method of collecting it. I dont have a trailer capable, nor a trailer licence. If i get it all going nicely and decide its worth keeping the truck long term then i'll look at it properly. Quote Link to comment Share on other sites More sharing options...
Bowie69 Posted June 23, 2009 Share Posted June 23, 2009 Thing is, an MOT fail truck is going to be 2-300quid, Yep, and you'd easily make upwards of £500 breaking it.... Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted June 23, 2009 Share Posted June 23, 2009 Thing is, an MOT fail truck is going to be 2-300quid Really? Right now I'd be surprised if you paid much more than that for one with an MOT on it - big, thirsty cars aren't exactly fetching a premium at the moment Quote Link to comment Share on other sites More sharing options...
Aragorn Posted June 28, 2009 Author Share Posted June 28, 2009 Okies, been working on the truck again this weekend. Changed the water pump, bled the system and ran it up to temperature and it seems to have stopped the oddness with the cooling system. So now i need to concentrate on the running issues. I got the clutch working, so took it out for a drive up the track to get a better idea what was happening. It seems once up to temperature it wasnt so much missfiring at full throttle, it just didnt accellerate. Lots of "sssssssssss" from the carbs drawing in air, but no associated roar from the engine. That would suggest to me that its more like a fuel problem than ignition? I had a look at the rotor arm and cap. The arm looked a bit odd, with wear on its leading edge. cap didnt look particularly bad though. Leads look a bit iffy, and i didnt get time to check the plugs out (i tried to remove one and gave up it was in that tightly!) but with it going flat at full throttle i'm not sure its actually the ignition system to blame, unless perhaps its the advance on the dizzy itself? So what i'd like to know is what diagnostic steps should i take. Clearly an ignition service is on the cards with new plugs, leads, rotor and cap, however i've no idea on what i should be doing to check the distributor itself or what to check for the fuelling... Any advice would be much appreciated. Cheers Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted June 28, 2009 Share Posted June 28, 2009 Have a quick suck on the vac pipe to see if the dizzy advances, if you just get a mouthfull of air then the advance diaphragm has probably perished - they can be replaced. Leads are cheap, any motor factors should be able to do you a set of Bosch or Lucas leads for £25 ish, FFS don't buy bling ones from the boy racer shop. The ignition system is as weak as a kitten in a blender so even if it's not your problem, giving it all the help it can get can't hurt - new NGK plugs are a good idea if you can persuade the old ones out. Sounds like a good poke at the carbs is next though - you'll need a live chicken, some holy water, and a tub of vaseline. I think that's what the haynes manual says anyway. Quote Link to comment Share on other sites More sharing options...
Aragorn Posted June 29, 2009 Author Share Posted June 29, 2009 Lol aye, wouldnt even know where to start on the carbs! Give me an EFI engine with a nice diagnostic port any day! I'll follow the instructions above about removing the tops of the carbs and cleaning up the guts. Anything else i should do while i'm at it? Also i'd like to raise the idle RPM's a little, as it seems just a smidge low for my liking. Which screw/knob/magicsetting do i need to touch to adjust that? Quote Link to comment Share on other sites More sharing options...
TheRecklessEngineer Posted June 29, 2009 Share Posted June 29, 2009 I think it is two sacrificial goats and some gold to raise the idle speed. Have a look at the back of the carbs - the throttle linkages are back there. The one on the passy side of the engine has the idle adjust. Quote Link to comment Share on other sites More sharing options...
Aragorn Posted June 29, 2009 Author Share Posted June 29, 2009 So the idle adjust simply holds the throttle open a little more? Or will i need to arse around with the mixture after opening up the idle? Quote Link to comment Share on other sites More sharing options...
TheRecklessEngineer Posted June 29, 2009 Share Posted June 29, 2009 That'd be the one, no need to play with mixture - only tweaking the throttle slightly. To paraphrase HFH: "Carbs are a bucket with a hole in". Quote Link to comment Share on other sites More sharing options...
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