Roger Posted July 22, 2023 Report Share Posted July 22, 2023 My Vitesse Mk I engine has a strange behaviour. It starts ok, and works fine for 3-5 minutes. But as soon as the engine starts to get warmer it looses power dramatically and finally dies after 10-15 minutes. First I suspected rubber slivers in the carbs (recently changed all hoses) so I took carbs apart, cleaned and re-assemblied. Fuel pump flow and pressure ok. Not vacuum in the tank, checked that. I’m quite sure that it is not related to carbs or fuel. Then I suspected a blown head gasked. Compression test: good and even pressure in all cylinders with cold engine. Could it be possible that the head gasket is ok on cold engine, but starts to leak when the metal gets warmer and expands? Thoughts? I will try to do a compression test on warm engine tomorrow. Another question: I have very limited knowledge about all things electric. Is there any electrical component that stops working when hot and could give this kind of problem. Thanks in advance! Link to comment Share on other sites More sharing options...
Nigel Clark Posted July 22, 2023 Report Share Posted July 22, 2023 Have you checked for a spark when the engine dies? Could it be an overheating coil or condenser for example? I would be looking for other causes of the problem before pulling the cylinder head. Nigel 1 Link to comment Share on other sites More sharing options...
Roger Posted July 22, 2023 Author Report Share Posted July 22, 2023 34 minutes ago, Nigel Clark said: Have you checked for a spark when the engine dies? Could it be an overheating coil or condenser for example? Thanks Nigel, no I have not checked that. Will do tomorow! Link to comment Share on other sites More sharing options...
Pete Lewis Posted July 23, 2023 Report Share Posted July 23, 2023 get a new condenser from the distributor doctor is my view think you can safely discount the head gasket and do a check that the coil is wired ign to pos and dizzy to neg . wrong way round can give really odd running problems Pete 1 Link to comment Share on other sites More sharing options...
Roger Posted July 23, 2023 Author Report Share Posted July 23, 2023 3 minutes ago, Pete Lewis said: get a new condenser from the distributor doctor is my view Thanks Pete, I think I have a few old condensers lying around so I will first try to replace it with what I have in the garage. It takes forever to get something from the UK with custom paper work etc. Long term solution will be a new one from DD. I also have several coils so I can test replacing that one as well (and check wiring). As mentioned I'm ignorant about these things, had no idea these parts could give heat related problems. You learn something new everyday on this forum! Link to comment Share on other sites More sharing options...
Roger Posted July 23, 2023 Author Report Share Posted July 23, 2023 24 minutes ago, Pete Lewis said: check that the coil is wired ign to pos and dizzy to neg . wrong way round can give really odd running problems Coil is wired as PO put it there (can't find + or - signs on it) so I will replace the coil with another marked one. PO put the dizzy 180 degrees wrong so coil could definitely be wired incorrect too! Link to comment Share on other sites More sharing options...
Pete Lewis Posted July 23, 2023 Report Share Posted July 23, 2023 this is an age old problem the car runs then plays up and stops you get out kick a wheel have a curse and it re starts i wish i had a £ for the ones ive found wrong over the many years an unmarked coil sounds a good contender i suggest dizzy doc for condensers as he tests all his own ,there are many with sod all inside the can worth a browse Delco condenser: RD7774, CD369, 829111,829107,1861709,1866049,18655972, 1869704,1882239, Lucas Condenser 484249, 400308, 407044, 54411935 / DCB105, 54413006, 23D4 22D 23D DM2 25D DM6 DM4 lucas distributor, Lucas condenser number 423871, GDC101. Condensor 405833 for Ford 8 and Ford 10, Lucas condensers from Distributor Doctor Pete 1 Link to comment Share on other sites More sharing options...
Roger Posted July 23, 2023 Author Report Share Posted July 23, 2023 These are my options: cannibalizing my Herald engine, was a runner when I took it apart, OR another unknown newish condenser with probably sod all inside. Not sure if a condenser from a Herald will fit in a Mk I 2000 engine but that is what I have so that is what I will use! Link to comment Share on other sites More sharing options...
Roger Posted July 23, 2023 Author Report Share Posted July 23, 2023 Update: Changed condenser to another one, but still same problem. It is difficult to describe, but the engine sound changes from cold to warm, noticably when listening to rear carb. The rear carb also "spits out fuel" when I turn the throttles and increase revs. I just have this feeling that cylinder 5 and 6 have a leak between them, but a new compression test when warm show good compression also when warm. This is driving me nuts! Next thing that comes to mind is if the inlet / exhaust gasket leaks (?) and the leak increases when warm?! It's a Mk I engine, I hate the design for inlet / exhaust bolts. Another discovery was that spark plug no 6 was wet and oily, all others dry. To be continued... Link to comment Share on other sites More sharing options...
Roger Posted July 23, 2023 Author Report Share Posted July 23, 2023 I try to upload a film... IMG_6980.mp4 Link to comment Share on other sites More sharing options...
Iain T Posted July 23, 2023 Report Share Posted July 23, 2023 (edited) Roger, have you checked the air piston diaphragm for splits? Without a good seal the vacuum cannot raise the air piston. Iain Edited July 23, 2023 by Iain T 1 Link to comment Share on other sites More sharing options...
Roger Posted July 23, 2023 Author Report Share Posted July 23, 2023 10 minutes ago, Iain T said: Roger, have you checked the air piston diaphragm for splits? Without a good seal the vacuum cannot raise the air piston. Iain Yes, checked that. I know that even a tiny hole can cause problems Link to comment Share on other sites More sharing options...
johny Posted July 23, 2023 Report Share Posted July 23, 2023 Is it possible an inlet valve is getting sticky on 4, 5 or 6 when it warms up although thought this would show on the compression test... Link to comment Share on other sites More sharing options...
Iain T Posted July 23, 2023 Report Share Posted July 23, 2023 (edited) 37 minutes ago, johny said: Is it possible an inlet valve is getting sticky on 4, 5 or 6 when it warms up although thought this would show on the compression test... I too think it could be a sticky inlet valve. It may be the slower revs cranking the engine when doing a compression test doesn't cause the valve(s) to stick? Something is creating the back pressure and it can only come from the piston compression chamber and non sealing inlet valve. It would also account for the loss of power. Certainly fuel droplets shouldn't be expelled the wrong way! Iain Edited July 23, 2023 by Iain T Link to comment Share on other sites More sharing options...
Roger Posted July 23, 2023 Author Report Share Posted July 23, 2023 Thanks Ian and Johny, I have also been thinking of the valves, I might have to remove the cylinder head. The reduction in power is dramatic, I barely limped home at 5-10 km/h. This is also confusing since I guess more than one cylinder must fail in order for power to drop so much? I have not replaced the ignition coil yet, will check that too just to be sure. Link to comment Share on other sites More sharing options...
johny Posted July 23, 2023 Report Share Posted July 23, 2023 Perhaps run it with the rocker cover off (shouldnt be too much oil) to see if you can spot any valves misbehaving? 1 Link to comment Share on other sites More sharing options...
Iain T Posted July 23, 2023 Report Share Posted July 23, 2023 (edited) Even with a dodgy coil or plug leads it shouldn't cause the blow back. As Johny said take the rocker cover off and first examine the valve springs. Then start the engine and make sure there is oil dripping out of the rocker shaft and arm. The rocker must be lubricated. If not let us know. Then inspect 4,5,6 cylinder valves. You can carefully put a finger on the rocker arm over the valves and perhaps feel any difference from the front three cylinders. If a valve is sticking you may be able to hear a noise as the rocker arm knocks the semi open valve head Be careful! Iain Edited July 23, 2023 by Iain T 1 Link to comment Share on other sites More sharing options...
Roger Posted July 23, 2023 Author Report Share Posted July 23, 2023 50 minutes ago, johny said: Perhaps run it with the rocker cover off (shouldnt be too much oil) to see if you can spot any valves misbehaving? Good idea! Will try that tomorrow Link to comment Share on other sites More sharing options...
Pete Lewis Posted July 23, 2023 Report Share Posted July 23, 2023 did you have throttles open on the compression test ??? Pete Link to comment Share on other sites More sharing options...
trigolf Posted July 23, 2023 Report Share Posted July 23, 2023 Just a thought..what symptom would a cracked cylinder head between an inlet and exhaust valve cause? Link to comment Share on other sites More sharing options...
Iain T Posted July 23, 2023 Report Share Posted July 23, 2023 16 minutes ago, trigolf said: Just a thought..what symptom would a cracked cylinder head between an inlet and exhaust valve cause? Unfortunately it looks like the head may have to come off for a full inspection but I don't know if a crack would cause that much blow back. Iain Link to comment Share on other sites More sharing options...
Mark B Posted July 23, 2023 Report Share Posted July 23, 2023 Does the piston lift and drop freely when lifted with your finger. It can bind if the dash pot is not central, or screws are tightened up unevenly. Link to comment Share on other sites More sharing options...
Roger Posted July 23, 2023 Author Report Share Posted July 23, 2023 46 minutes ago, Pete Lewis said: did you have throttles open on the compression test ??? DOH!!!! 😖 I think I forgot. What impact would that have on the test? Will try again and make sure to have them fully open. Link to comment Share on other sites More sharing options...
Roger Posted July 23, 2023 Author Report Share Posted July 23, 2023 15 minutes ago, Mark B said: Does the piston lift and drop freely when lifted with your finger Yep, no problem there. Nice "clonk" when tested. Link to comment Share on other sites More sharing options...
Iain T Posted July 23, 2023 Report Share Posted July 23, 2023 36 minutes ago, Roger said: think I forgot. What impact would that have on the test? It's stops the cylinders sucking in air so the compression readings are incorrect. Iain Link to comment Share on other sites More sharing options...
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