davehummell Posted November 27, 2016 Share Posted November 27, 2016 Hello, I would like to know what the cylinder cranking pressure should be for a end 673 I removed all the injectors and made sure the batterys were up and I got 300 lbs on all 6. I wonder if it is to low? I think the 675 or 676 were 400 lbs. I just cranked the engine like you would a gas engine. Thank you Dave Quote Link to comment https://www.bigmacktrucks.com/topic/47802-compression-test/ Share on other sites More sharing options...
mrsmackpaul Posted November 27, 2016 Share Posted November 27, 2016 I would have thought closer to or above 400 but if they are all around the same maybe thats what they should be Paul Quote Link to comment https://www.bigmacktrucks.com/topic/47802-compression-test/#findComment-353213 Share on other sites More sharing options...
theakerstwo Posted November 28, 2016 Share Posted November 28, 2016 END673 is a hi compression piston so 300 is on the low side but what problem are you having?All of them are the same so its not missing from low compression so that part is good to run. Quote glenn akers Link to comment https://www.bigmacktrucks.com/topic/47802-compression-test/#findComment-353214 Share on other sites More sharing options...
j hancock Posted November 28, 2016 Share Posted November 28, 2016 An END-673E is 500-530. ENDT-673C, ENDT-675 and the ENDT-676 is 445-475 for comparison. Quote JimIt doesn't cost anything to pay attention. Link to comment https://www.bigmacktrucks.com/topic/47802-compression-test/#findComment-353216 Share on other sites More sharing options...
davehummell Posted November 28, 2016 Author Share Posted November 28, 2016 This truck has me really thinking, It will not start when its cold without just a wiff of ether. I replaced fuel lines and fittings to were it keeps the fuel right there. I had the heads off and replaced the gaskets and went over the valves . readjusted valves and looked things over in the cylinders no damage in liners or piston crowns. I got 6 different injectors but I am going to have them checked 4 don't hit as hard as the other 2 they do slow the engine down when you crack them open. If I have to I will send the pump out to be checked. It seems to have equal pressure when you loosen the lines but that is just judgement call on the pump. I Thought it should have more pressure on cranking but it seems funny that all are that close and 300 lbs. I think this truck sat for a spell when I first fired it up and let it run for about an hour it slobberd oil out the exhaust ports, manifold is not on the engine so I could watch the ports. I then took it for a drive out around the block about 3 miles and now the ports are dry as a bone so I wonder if I run it 10 or 15 miles if it would help it ? Thank you every one that took the time to respond. Dave Quote Link to comment https://www.bigmacktrucks.com/topic/47802-compression-test/#findComment-353241 Share on other sites More sharing options...
theakerstwo Posted November 28, 2016 Share Posted November 28, 2016 There is more things that can cause it to not start when it sets.One thing can cause a problem is loosing it fuel prime as well as low fuel pressure.Timing needs checked. 1 Quote glenn akers Link to comment https://www.bigmacktrucks.com/topic/47802-compression-test/#findComment-353242 Share on other sites More sharing options...
gearhead204 Posted November 28, 2016 Share Posted November 28, 2016 how much blow by does this engine have while running? if there is a lot you may need to replace some worn rings, how did the liners feel at the top when you had the heads off? could this engine have been dusted? the blow by will tell if it has. Quote Link to comment https://www.bigmacktrucks.com/topic/47802-compression-test/#findComment-353245 Share on other sites More sharing options...
davehummell Posted November 28, 2016 Author Share Posted November 28, 2016 At my age I figured out I know a lot less than I did when I was in my youth. So I have to ask what is dusted mean? I guess I had heard it before but I can't remember it. I am going to end up pulling the pistons and rering them. All 6 injectors were just pushing fuel so I think the cylinders are glazed, before I do I will try to reseat the rings with bonami cleaner we sometimes had to help out an engine on the dyno. Quote Link to comment https://www.bigmacktrucks.com/topic/47802-compression-test/#findComment-353327 Share on other sites More sharing options...
mrsmackpaul Posted November 28, 2016 Share Posted November 28, 2016 dusted means has dust got in the engine somehow first things first when you very first wind the motor over does any smoke come out the exhaust, this will tell you if you are loosing fuel when you did the compression test did you squirt any oil in each pot to see if the compression changed it will tell you if its the rings or the heads you are loosing compression thru The problem when you are changing heaps of different things at once hoping to fix it you will never know what the problem is was as so much was changed When you had the heads off did you sit them on there side and fill the ports with petrol to make sure they were sealing well ??? I always do the the real basics first as 9 times out of 10 the basics lead me straight to the problem And please dont think Im been a smart ass here by been to simple good luck Paul 1 Quote Link to comment https://www.bigmacktrucks.com/topic/47802-compression-test/#findComment-353328 Share on other sites More sharing options...
davehummell Posted November 29, 2016 Author Share Posted November 29, 2016 I don't know the history of this truck. The first thing I did was replace the filters and fuellines and fittings that looked suspect and then I replaced primerpump and pulled off the transfer pump and seated the poppet valves. and replaced the metal return line and rubber compression rings on the ends plus removed the check valve and made sure it worked. added gauge in line, now I know I am not losing prime. The rear head was leaking oil an I can't stand that so I pulled the heads and cleaned and checked the deck and heads with a machinist straight edge I seated valves up with paste and checked with srewloose spray they were real good before I touched them up. It shows fuel out the exhaust pipe now when you crank it. I replaced the 6 injectors with ones I had checked on a tester. just now I went out and squirted oil in cylinder and it went from 300 up to 400 so that about says I will be looking for at least rings or more parts . 1 Quote Link to comment https://www.bigmacktrucks.com/topic/47802-compression-test/#findComment-353337 Share on other sites More sharing options...
mrsmackpaul Posted November 29, 2016 Share Posted November 29, 2016 (edited) thats good news and bad news hey good news you know were the problem is now ,bad news it's not a simple $5.00 fix but you can work from here Paul one thing to always keep in mind I reckon is in Australia right up until the late 90's early 2000's almost all Macks were air start dunno why but thats the way we like them and with air start you only get one shot of say 10 seconds at the most to fire most likely only 5 seconds I know it aint long but these Mack motors when in fairly good nick fire first piston to the top even if they have been sitting for a long time they are real good starters every time so if you cant start it on a starter motor you got dramas !!!!!! .Air start soughts out the good motors from the bad in a instant seeya Edited November 29, 2016 by mrsmackpaul Quote Link to comment https://www.bigmacktrucks.com/topic/47802-compression-test/#findComment-353380 Share on other sites More sharing options...
Hobert62 Posted November 29, 2016 Share Posted November 29, 2016 When my dad would build small cam cummins back in the day they would use an offset key to retard the cam timing. Made for better running but harder starting on cloudy days. I think someone mentioned before double check the timing while your at it. Quote Link to comment https://www.bigmacktrucks.com/topic/47802-compression-test/#findComment-353418 Share on other sites More sharing options...
davehummell Posted December 12, 2016 Author Share Posted December 12, 2016 Well I thought I would give a update on this disaster I bought. I did a compression test as mack recommends and I only had 375 lbs at 1000 rpm mack states it should be atleast 500. So I pulled the pistons out but no resistance when I pushed the rods and pistons out Liners were glazed up real bad the 6 injectors that were bad didn't help any. Piston are good, rings are weak on tension. I have dealt with cook brothers truck parts for 25 or so years so tom and jeff found me ring sets and 20 under rod bearings. I guess I will pull the mains and see what I have to scare me some more. Dave 1 Quote Link to comment https://www.bigmacktrucks.com/topic/47802-compression-test/#findComment-354863 Share on other sites More sharing options...
theakerstwo Posted December 13, 2016 Share Posted December 13, 2016 If rings are worn out then the liners are also.Ifthe liners and rings are worn out so is the valve guilds and valve stems. Quote glenn akers Link to comment https://www.bigmacktrucks.com/topic/47802-compression-test/#findComment-354973 Share on other sites More sharing options...
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