Timing Belt marks

[reztoration]

81 Maxima automatic with 300,000 miles; previous owner tried unsuccessfully to replace timing belt and gave up. I followed the manual, noticed the text seems to say something different than what's illustrated. The manual says 20 cogs between the marks, yet it illustrates aligning the belt marks with the IP pulley & crank pulley marks. Which is correct 20 cogs mark to mark or 20 cogs between the marks(which makes 22 cogs mark to mark)? I've currently installed it as illustrated, 20 cogs, matching the belt marks with the pulley marks. Pretty sure I have the right marks, although my IP pulley has three marks: A,B, & blank. (I used the B) I also replaced the fuel and primed the system. She fired up, but initially clattered (not knocking) loudly and spewed gray/black smoke. It settled down but still smoked after warming. When putting it in gear, it stalled if I didn't increase the revs, which brought back the loud clatter. Not the diesel behavior I'm familiar with. It'd be great if I just have the wrong combination of variables & not a tired LD28. Appreciate any help.[/i]

[goglio704]

The timing is too far advanced. The twenty cogs includes the marks. The first marked cog would be one and the second would be twenty. The marked cogs will align with the the mark on the crank and IP. I just went through this myself. Did you make sure the number one cam lobe was in the correct positon?

Good info on this in the FAQ. Also, have a look here for some additional info.

You need to make sure which keyway in the sheave is actually installed on the key of the IP. Take the nut loose and use a small probe in each keyway to determine which keyway actually has the key. If yours is like mine the key should be in the keyway marked AB if you are qoing to use the B mark for the belt.

Feel free to ask questions if this is clear as mud.

P.S. Do you need a set of '79 350 diesel heads with injectors? These are the pencil type injectors.

[reztoration]

Thanks, I'll check it out today. I did rememember to set the cam to TDC, but I'll remove the nut to physically, rather than visually, check the keyway.

Ironically, I haven't had any trouble with the Olds; fortunately, I have the later engine which may be slightly different to the 78-80 heads/injectors. I'm running 50% WVO, so she might develop "hardening of the arteries."

I'll be back. Thanks.

[reztoration]

Thanks for the advice; even though I was sure I had done everything correctly, I simply failed to verify TDC on the last try.

What a sweet engine! 300,000 miles - still strong and smooth.

Thanks Again,
Ike

[goglio704]

Glad to hear a good outcome. Keep in touch.

[gus brewin]

I have an LD-28 in a 27' Albin Boat. I am in the process of rebuilding the engine. I just finished putting it back together. It would not start - I had to take it all back down. Is there anyone out their that has rebuilt one that I could call on the phone and ask questions to? Or that would e-mail me? I live in Derry, New Hampshire (603)434-5957

Thanks,
Gus

[asavage]

I've never had one apart, beyond the intake manifold, valve cover, and IP belt. And lots of wiring.

[goglio704]

Ask away Gus. You're in the right place. While I'm sure there are several people here who would help you one on one, it defeats the purpose to some extent. There is no such thing as a stupid question. There are some very knowledgeable people on here (I am not one of them, but I get lucky sometimes). Give us some background info on what has been done, and we will go from there.

[asavage]

I should add, that apart from the usual fuel system bleeding issues (not getting all the air out before cranking) and the GP system foibles, (are they OK, and are they really getting enough voltage?), a no-start problem on a rebuilt engine boils down to:

• Compression: do you have enough? IE are the rings in right, is the piston-to-cylinder clearance within spec?
• Cam chain timing (camshaft timing): is the cam in time? If not, you probably already have bent valves: no room for error on diesels in the cam timing department, which is why you always bar a diesel engine over by hand after assembling.
• IP timing: belt-to-sprockets timing is an easy one to screw up, esp. since the IP sprocket has multiple timing marks, but even the IP mounting itself can be varied enough to prevent starting. Did you match-mark the IP-to-housing before disassembly? If not, did you mount a dial indicator in the ass of the distributor head and use the factory IP timing method? If "no" to both, you should back up and do the latter, as you cannot time this engine "by ear", and diesels are much more sensitive to timing changes than gassers; 2° difference is appreciable for a diesel.

Hope this helps.

[gus brewin]

Dear Al & Matt B,

Thanks for your response. I will start from the beginning. I am working with my neighbor a retired diesel mechanic. He has never worked on an over head cam though - he has only worked on Volvo's & Mercedes. I am a truck driver not a mechanic. I'm trying to understand. Here goes.

We took the engine out of my boat because the head gasket was leaking.
We checked the crank bearings - they were like brand new.
So we did not do the bottom of the engine. Their are not may hours on the engine to begin with.

We sent the head out. Sent the fuel pump & injectors out. Starter & alternator out. Put all new gaskets in it. Put it all back together.

Would not start #1 no oil pressure#2

1st question is - Do we have the timing chain in right? We have a manual
How do you prime the oil pump? and how do you prime the fuel pump?
Is the chain normally hard to get on & off the cam sprocket?

We have it all apart again. We are ordering a new gasket set and timing chain. I guess we need to be sure before we do this one more time.

Thank you very very much

Gus

[asavage]

Would not start #1 no oil pressure#2

1st question is - Do we have the timing chain in right? We have a manual
How do you prime the oil pump? and how do you prime the fuel pump?
Is the chain normally hard to get on & off the cam sprocket?

Member TheDieseliminator (Salvy) has had the head off his LD28, so perhaps he'll weigh in on this too.

Member Pascal has had trouble obtaining oil pressure on his newly-acquired LD28 too. You might read this short thread, though it's still a problem "in progress".

Priming the fuel pump: There should exist a priming pump external to the engine somewhere -- on the LD28 installations in the Maximas, the priming pump is integrated into the top of the fuel filter head. IIRC, the IP's return line must be removed during the priming procedure (I may have that wrong; I have not read that procedure in a while). Which manual do you have for the engine?

On priming the oil pump: the traditional method is to pack the pump with petroleum jelly. That's for a completely dry engine. I suspect that if you pre-fill the oil filter and run the engine on the starter for a bit (with the glow plugs removed) it will likely self-prime, unless you took the oil pump apart and completely removed all the old oil. The oily surfaces provide some sealing for the trochoid pump.