iana Posted August 21, 2019 Report Share Posted August 21, 2019 Today hasnt been a good day, after a good drive in the vitesse the plugs we removed to check the state of tune of the carbs, adjustments made but the car was running badly. so in the end we did a compression test on the vitesse, the results are 220 , 140 , 140 , 140 , 75 and 75. More investigations to follow but I'm assuming cyclinder 5 and 6 would suggest a head gasket failure, what would the cause of cyclinder 1 be? Link to comment Share on other sites More sharing options...
poppyman Posted August 21, 2019 Report Share Posted August 21, 2019 Did you check it more than once? If not i would suggest a faulty tester maybe.... Tony. Link to comment Share on other sites More sharing options...
Clive Posted August 22, 2019 Report Share Posted August 22, 2019 Plus....all done a brittle wide open? Worth doing a set with a couple of squirts of oil in each cylinder too, so dry then wet. Link to comment Share on other sites More sharing options...
iana Posted August 22, 2019 Author Report Share Posted August 22, 2019 We tested all 6 cyclinders then tested the first one again, and got the same reading. Clive, I’m assuming brittle is throttle (predictive text) - no the throttle wasn’t fully open Link to comment Share on other sites More sharing options...
Clive Posted August 22, 2019 Report Share Posted August 22, 2019 Sorry, throttle.... Yes, should be done open so no restrictions. (And best to take all plugs out too) Link to comment Share on other sites More sharing options...
JohnD Posted August 22, 2019 Report Share Posted August 22, 2019 Compression testing is most procedure dependant! Worth practicing. Have the engine fully warmed (you did that), WIRE the throttle wide open*, have all the plugs out, observe the reading to stabilise each time. Do it two or three times, especially if not a procedure familiar to you, so have a running modern connected by jump leads, to ensure that a draining battery is not a cause of poor operation. The oil in the chamber is a secondary test, NOT part of the process. It promotes sealing of the rings, and will raise compression briefly. If it doesn't, then a low compression is due to a valve seal problem. How is the car "running badly"? What made you do a compression test? John *PS If you are on carbs, it takes a finite time to raise the piston, even with WOT, because of the dashpot. This delays achievement of true compression. Remove the dashpot pistons, and ideally the carbs, whereupon no throttle wiring is needed! J. Link to comment Share on other sites More sharing options...
johny Posted August 22, 2019 Report Share Posted August 22, 2019 As its going to affect all cylinders I think whatever procedure you use its equal readings and not the actual figures reached thats most important. And surely if sparkplugs are out you dont need to worry about the carbs as we're only talking starter motor engine speed? Link to comment Share on other sites More sharing options...
JohnD Posted August 22, 2019 Report Share Posted August 22, 2019 Don't you think the spark plug holes are a bit smaller than the intake manifold? J. Link to comment Share on other sites More sharing options...
johny Posted August 22, 2019 Report Share Posted August 22, 2019 of course and at 7000rpm it would make a difference but on the starter motor no.... Link to comment Share on other sites More sharing options...
Clive Posted August 22, 2019 Report Share Posted August 22, 2019 Removing plugs means no compression on the cylinders not being tested, so the starter motor has a much easier job. No other reason. And as all plugs need to come out at some point, do them all at once. Just mark the leads. Link to comment Share on other sites More sharing options...
Pete Lewis Posted August 22, 2019 Report Share Posted August 22, 2019 as said its important there is no restriction in the intake , rather than remove the air pistons hold them up /open with a slim block of anything handy a good battery have the engine Hot. throttles and air pistons are OPEN all plugs out so there is no drag on the starter motor repeat to see reading are repeatable the 220 figure on No1 is abnormal a 'rough' guide is atmospheric x comp ratio so 14.7 x 8.5 = 125 low results often down to un balanced and closed throttles so free up the intakes loose the plugs and have a read about soiled plug failures Link to comment Share on other sites More sharing options...
johny Posted August 22, 2019 Report Share Posted August 22, 2019 41 minutes ago, clive said: Removing plugs means no compression on the cylinders not being tested, so the starter motor has a much easier job. No other reason. And as all plugs need to come out at some point, do them all at once. Just mark the leads. Ok Link to comment Share on other sites More sharing options...
johny Posted August 22, 2019 Report Share Posted August 22, 2019 ahhh realise Ive had a senior moment in thinking the cylinder being comp tested could drawn air in through the spark plug hole but of course thats where the tester is installed! doh🙄 No idea what could give a high reading like that: wrong piston, huge build up of carbon? Link to comment Share on other sites More sharing options...
Steve P Posted August 22, 2019 Report Share Posted August 22, 2019 My new 1500 was 190,195,210,210, before it grenaded after 500 easy miles. Don`t know the history of your engine but If yours was mine i would whip the head off and have a look at the valves and seats. Steve Link to comment Share on other sites More sharing options...
Nick Jones Posted August 22, 2019 Report Share Posted August 22, 2019 7 hours ago, johny said: No idea what could give a high reading like that: wrong piston, huge build up of carbon? One possibility, given that the original test wasn't done with the throttle open, is that the manifold gasket has failed on that cylinder so it was getting more air than the others. That would certainly contribute to rough running. 5 & 6 @ 75 psi won't be helping either, especially if it is the HG blown between them. If it's a Mk1 engine, HGF between cylinders is quite common. Nick Link to comment Share on other sites More sharing options...
JohnD Posted August 23, 2019 Report Share Posted August 23, 2019 Pete's formula for compression (Atmospheric x CR) is attractive, but theoretical, and no doubt is a valuable rule of thumb (the best rules!) But to compare the pressures found by different operators, using different gauges, is definitely not valid. The conditions of the engines and the weather on different days, in different places, and that compression gauges are not precision instruments, not calibrated and often roughly treated, make that so! The only valid comparison is one engine, across the block, or else two engines, carefully warmed up to the same state and prepared and tested on the same day in the same place. Try again, Iain, bearing in mind all the advice above! John Link to comment Share on other sites More sharing options...
dougbgt6 Posted August 23, 2019 Report Share Posted August 23, 2019 All very fascinating, but let's not loose sight of what the compression test is for. Are they all roughly the same? In this case, no. Very much not roughly the same. The head has to come off and then we'll find out what's wrong. Doug Link to comment Share on other sites More sharing options...
iana Posted August 23, 2019 Author Report Share Posted August 23, 2019 Thanks all, the issue is beyond my abilities to fix so have sought help. I'll update after further investigations as to the issues found, the plan is to re-do the compression test tomorrow to confirm the differencies between the cyclinders and take it from there. I'm certainly on a steep learning curve with this car! Link to comment Share on other sites More sharing options...
Pete Lewis Posted August 23, 2019 Report Share Posted August 23, 2019 its the old saying they have more reasons to sell it than you have to buy it but when all the trials and tribulations are over .....great cars for a smile and fun driving keep asking we can help where we can pete Link to comment Share on other sites More sharing options...
iana Posted August 25, 2019 Author Report Share Posted August 25, 2019 After a day of working on the car with a local area member, the compression test was redone to confirm the results, this gave similar results so the decision was made to remove the head and see what was found. The head gasket had failed between 5 / 6 see picture (the oil was to check the pistons were ok). The head was washed down and checked, I need to order parts now so there will be a delay until later this week. Its a 1967 MK1 vitesse, any recommendations of a supplier (i was going to use Paddocks). Theres a few other things I need to order to put the car back together - any ideas where I could get a bottom radiator hose? They appear out of stock at the places I'd normally use. Link to comment Share on other sites More sharing options...
Pete Lewis Posted August 25, 2019 Report Share Posted August 25, 2019 in stock at rimmer bros https://rimmerbros.com/Item--i-GRID007807 for head get some HD washers from canley they do HD nuts as well if needed i would use canley for a gasket kit . look at your old washers bet they have deformed under the torque and thats why the gaskets gone .the load on the nut has relaxed ...very common problem pete 1 Link to comment Share on other sites More sharing options...
dougbgt6 Posted August 25, 2019 Report Share Posted August 25, 2019 iana, Well done! But what news of number 1, with it's abnormally high compression reading? Doug Link to comment Share on other sites More sharing options...
iana Posted August 25, 2019 Author Report Share Posted August 25, 2019 Doug when the compression tests were redone with a different guage the readings 1-4 were all around 120 - 130 and 5/6 was down at 40 (can't remember the exact numbers). What we did find however on stripping the manifold was that the recently fitted manifold gasket was poorly fitted around cyclinder 1 and also the quality wasnt the best (this had been done by my local garage so Ive learnt my lesson and wont bother using them again and I will be wary with the parts supplier as well) 1 Link to comment Share on other sites More sharing options...
Pete Lewis Posted August 25, 2019 Report Share Posted August 25, 2019 I would remove the studs and with an oily wet and dryon a flat hard block really clean the block back to clean steel , no deposits note the suds have a slot to allow any oil down the thread to escape and some are longer ( to fit odd bits. tube brackets etc. onto at the back of the head ) easy way to pop the valves out is a socket under the head, another socket over the collets give it a good whack and the collets pop out needs a spring compressor to re fit though. if you use a SC to remove it pays to use the socket and whack to break the initial stick of the collets or you can fail the tool before the collets let go. they do get a good grip always keep a cornflakes packet to make 12 holes marked front so each valve and push rod go back where they came from pete Link to comment Share on other sites More sharing options...
daverclasper Posted August 25, 2019 Report Share Posted August 25, 2019 I understand the Mk1 manifold is not a great design as gasket sealing goes and this is compounded by new gaskets not being so good. I have seen old threads on this problem and folk considering using 2 gaskets, though no more info on this. PS. Apologies if this info has given you, yet another headache, but thought it worth mentioning?. Hopefully others may have more conclusive info on this. Dave Link to comment Share on other sites More sharing options...
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