88 4 valve no start.

[63BMack]

88 R model with a 4 valve, it turns over like it doesn't have much compression. It only has around 300,000 miles question is would the injector pump or injectors make it sound like low compression. I took the puff limiter off and the rod moves easily doesn't  feel like the rack is stuck. No metal in the pan from rings or cam. Anyone have any ideas about what to check next. Won't run on starting fluid either. 

[Joey Mack]

just a thought...  check the valve lash..... seem's odd,,  how long has it been sitting? how long have you had the truck, and what do you know about repair history?  That engine is a tough S.O.B.   I saw one run  with a rod through the block,  it loaded itself on and off the trailer to the shop... ether is a bad tool/drug if abused....   ok,  look forward to the fix for this one..  Go E-6!! jojo

[Onyx610]

Yes they are, in school someone forgot to put the rod bearings in it and ran it for a good 10 min through the rpms. Another time two liners dropped and as the crank came around each time it ate more and more until the liners were gone. There were a few more “mishaps” with that poor engine but it still runs to this day from what I hear….

[63BMack]

Just got the truck, don't know how long it's been sitting. Don't know anything about repairs. I might see about valve lash, it seems a couple of valves are more loose than some of the others. I have overhauled 2 valves engines but don't know much about the 4 valve. I have a Mack e6 4 valve overhaul manual, I think I will try that first. The guy just said it had a tick in the top end. Thanks Guys I will let you know what I find out. 

[fjh]

Quick check of the pan plug should  tell the tale on this if there are pieces on the plug there you likly have a cam failed or the engine has been over speed and bent some valves ! Just a place to start! also  you can pull the valve covers and check to see if the push rods are straight! 

[63BMack]

No metal in oil pan, stuck a magnet in there still nothing. I will adjust the valve's an check push rods, 

[fjh]

Sorry didn't read the whole post my bad  ! no metal in the pan! So I have seen the pump drive fail on these its a fiber coupling ,is it possible for you to remove the top rear cover of the fuel pump 6 -1/4 inch  bolts  and see if the pump is turning! althou this has nothing to do with compression its somthing to check!  But if it wouldn't fire on ether its likley a compression issue as you are saying!

In my opinion your heading in the right direction checking the valve set and push rods! If you got bent rods the engine has likley seen an over speed event!

Edited September 30, 2021 by fjh

[63BMack]

That's alright, I will check the pump drive too never thought about that. The pump has one of those bolts that the head is plugged, I might loosen one of the injector lines to see if fuel comes out. I will probably set the valve's first and check the push rods. Thanks for the  information. Your alot of help, I appreciate that. 

[63BMack]

I finally got the heads off, #1 cylinder dropped a valve. Front head is junk, aluminum pieces are in the other cylinders so sounds like time for an inframe major, anyone have any suggestions on where to get a pair of remanufactured heads and overhaul kits for an 88 e6 4 valve. Thanks everyone for the help trying to figure out what was wrong with it. 

[Joey Mack]

Sorry,  but when you are done ..... you will have one hell of an engine.. jojo

[JoeH]

Our old trucks work every day, we put Mack dealer parts in them, but some guys like PAI aftermarket Mack parts.  Haven't tried them myself.

 

We have a '70 2 valve that dropped a valve once. We got away with one head and one cylinder/liner kit.

Edited October 9, 2021 by JoeH

[Joey Mack]

I have built 2 engines with PAI kits. the engine kit contents are better than Mack's kit... i have measured the liners, length, O.D. and I.D. with my mic's..  they were "spot-on". I mic'd the pistons, rings etc...  all part's spec'd out fine... Hell, the kit's even came with new piston cooling tube's and ball's...   One that I built was a '90 E-7 mechanical, the other was an '05 ASET-I...The '90 is running great after 18 months, the ASET is six months old and doin what a Mack need's to do...  I will certainly use these kit's again... When you build the engine, take all of the normal measurement's on the block, and machine it as needed, ie: cutting counterbores and decking.. I also have used P.A.I. heads. 👍..  I hope that other's offer thier opinion's..  I'm not a Guru with these kit's, just have had success...and the cost is about 1/3rd less if not a bit more..   Jojo

[theakerstwo]

There is nothing wrong with PAI parts.

[mrsmackpaul]

I would go along with  the view on PAI parts, I have never had a bad experience with them yet 

 

 

Paul

[Hayseed]

6 hours ago, mrsmackpaul said:

I would go along with  the view on PAI parts, I have never had a bad experience with them yet 

 

 

Paul

Me either, Paul.

[63BMack]

Thanks guys, I'm checking on the price difference between Mack parts and PAI. I will probably go with PAI. I still have to pull the pan to see if it's standard. I'm going to look the cam over real good even though I didn't have any metal in it. I gonna hate it when the old Mack mechanic's and Mack parts guys are gone. I'm almost 65 years old so I guess I won't have to worry about that. Just have a couple of old trucks to take to truck shows.Thanks again. 

[Joey Mack]

I hope the good lord lets me stick around a while...... I wanna be one of the old timers that helped 'Me'  along the way... so I can help others, even Old Timers... 😉 Jojo

[63BMack]

I hope your around a long time too, I read your post regularly and your full of knowledge on Mack Trucks is priceless. I always look forward reading what's up with the Mack engines. Don't really care about any other brand. Stay safe. Ron

[fjh]

15 hours ago, 63BMack said:

Thanks guys, I'm checking on the price difference between Mack parts and PAI. I will probably go with PAI. I still have to pull the pan to see if it's standard. I'm going to look the cam over real good even though I didn't have any metal in it. I gonna hate it when the old Mack mechanic's and Mack parts guys are gone. I'm almost 65 years old so I guess I won't have to worry about that. Just have a couple of old trucks to take to truck shows.Thanks again. 

So just  something to think on Here ! If indeed this engine had an over speed go on! These old style lifters didn't take kindly to being over speed conditions!  The work face is brazed on and would shatter or crack! Personally Knowing what I have seen over the years here ! If indeed this engine got over sped  and  you are doing all this work , its worth the extra 500 or 1000 bucks to pull the cam and buy A SET of lifters from PAI  and replace em!   We just done a Cam here Sept 20th 2021 on a 88 RB . Mack parts  was twice the price  PAI did'nt have the cam at that point So we  was stuck with the Volvo Criminalized pricing  for the Cam  but PAI  had the new style lifters for a third less! and in this instance the lifters are the weak point! and if the truck has the old style lifters It may be a safe bet to change em! In my opinion  Not worth taking a chance if your going this far! 

 

Just Sayin!

Edited October 11, 2021 by fjh

[Joey Mack]

"F" makes a lot of sense with his post...  Pay attention to him...  jojo

[63BMack]

Thanks for advice, can you use new lifters with an old cam if the cam is good. Another question what RPM is overspeeding, I have seen engines 2300 to 2400. Just wandering what is a safe maximum RPM.

[Joey Mack]

Generally, if the cam is straight, and all journals and lobes meet Mack spec, then it is re-usable..  I just recently put the old cam back in an Isuzu 4HE1 because it was well within spec. and the owner is trying to cut cost...  Not all will agree, but there are spec's for a reason...  I also put a cam in my own S.B. chevy 350, that I  took out of my 400, when I built the 400... the 400 cam was in great shape and the 350 cam had visible wear. I did put new Melling lifters in it...  My 350, runs great...  it's in my 1-Ton....  There should be some more opinions on the way...  as far as over speed...  My GUESS is anything above 2400 is too much for you're engine...  F, And V, and Glenn and others may know better than me on this one..  Jojo

[fjh]

16 hours ago, 63BMack said:

Thanks for advice, can you use new lifters with an old cam if the cam is good. Another question what RPM is overspeeding, I have seen engines 2300 to 2400. Just wandering what is a safe maximum RPM.

 

Yes old cam and new lifters is fine !  If the Cam looks usable it probably is! The problem you have there is Your working with an unknown ! And We are working with what you are telling us! In turn we are offering up the best advice according to our experiences! An over speed would constitute anything much over governed RPM !Back in the day this would happen a fare amount specially on a V8 Because these engines were so quiet! It would sneak up on ya on a down hill with the engine brake on! It Would be easy to look down at the tach and say Holy Crap!!!!! 2500 RPM 😡 Unless you got a good ear and tuned in to your unit Its sure to happen ! Very easy to do! Answer to the question Safe max RPM is Governed RPM! the engine can probably tolerate 2600 How ever Do you want to go there?? 

 

Edited October 12, 2021 by fjh

[Vladislav]

5 hours ago, fjh said:

😡the engine can probably tolerate 2600 How ever Do you want to go there?? 

 

Definitely by re-setting the governor

[Steve L]

It sounds like there are still old style lifters about. We had the new ones here in OZ some 30 years ago, so I would have guessed near all would have been replaced by now . 
I need a PAI E6 rebuild kit and rod bolts. Do PAI sell directly? If not who’s the best to buy from in USA Here Ovlov quoted me over 6000 + tax without rod bolts, they make the kit up with individual parts, no more all in one box.  The last kit I purchased was over 10 years ago, it was packed in Mack packaging but was branded made in India, still going strong though. 

Edited October 13, 2021 by Steve L