Compression questions, engine pics, and timing guides?

[gs14racer]

Hey guys im over from the vh forum, doing the swap into a 240sx, and had a couple questions.

Ok so while im waiting for the transmission id thought id check out a couple things on the motor. First thing this motor hasnt been started in about 7-8 weeks.

So compression check

Here goes

Drivers bank 150 - 155 - 162 - 180

Pasng. bank 170 - 140 - 155 - 155

So i think maybe the rings are stuck from sitting so long So i pour a cap full of marvel mystery oil down each plug hole and let it sit for about 2.5 hours

Then i recheck

Drivers bank 180 - 210 - 190 - 190

Pass Bank 180 - 180 -180 - 180

Think this is ok guys?/?

Next thing pulled off one of the valve covers, looks pretty clean for a high milage motor what do you guys think?







Lastly decided to check for timing guide replacements so removed the pass side cam gear cover and sure as **** found peices of it, though the motor has great oil pressure and ran great before so im pretty sure no damage was done.

[qship96]

looks like it didnt recieve proper service to me-looks like an old tired motor with infrequent oil changes.

[Ozzie]

Yeah, that looks like a lot of varnish for a VH.....

I can't comment on the compression, because I am not sure what it was from factory.

Definitely replace the timing chain guides, and pull the sump off while you have the engine out, as I'm sure you will find LOADS more pieces in there. Clean the oil pickup while you're in there picking out the guide pieces.

[ScottJackson]

I've seen much worse gunk build-up than that. I agree, pull the pan and while you're in there, may as well check rod/main bearings (toss in new ones if they're showing copper).

[maxnix]

Next thing pulled off one of the valve covers, looks pretty clean for a high milage motor what do you guys think?







Lastly decided to check for timing guide replacements so removed the pass side cam gear cover and sure as **** found peices of it, though the motor has great oil pressure and ran great before so im pretty sure no damage was done.

Looks pretty abused to me with high OCI.

One has to reconstruct and weigh the chian guides to determine if some is missing in the sump. Wait until you see cahin marks or streched oul pump chain beofre you assess damage.

[gs14racer]

There isnt any sludge in the motor, its just a lot of varnish. My plan at this point is to change the chain guides , tensioners , oil pump tensioners ,and oil pump chain. The motor ran fine before we pulled it smooth idle and good power.

Maybe ill start building up another one spare motor.

[gs14racer]

As far as the sump is concerned, i have to remove it to modify it a bit so thats not a problem.

Where should i look for chain marks?

[carfrk666]

nasty lookin sledge, but about ur compression, thats not bad for an engine that has been sittin for a couple months, when u add oil to the cylinders the compression will always increase alot like that, but overall i wouldnt worry about ur compression being uneven or anything, i would worry more about the nasty looking oil buildup

[PopPop]

Motors compression numbers are not bad! Looks like long time between oil changes and no use of flushing agents or MOA but, not a lot of sludge buildup just baked on oil/varnish stains. Look at this engine with over 200.000 miles.

[Ozzie]

As far as the sump is concerned, i have to remove it to modify it a bit so thats not a problem.

Where should i look for chain marks?

Check around the shaft of the oil pump sprocket, and the surrounding areas of the oil pump.If the slack side guide gives way on that bank, the chain droops down and runs along the surrounding areas, gouging into the metal

[gs14racer]

It appears that only the passenger side guide broke, the drivers side one feels like its about to break. Doesnt look too bad to me. Heres some pics.

Oh and another question is the oil pump drive sprocket on the crank supposed to rotate freely? It appears to me to not have a woodruff key and is solely held in place by the crank pulley?

[Ozzie]

Yes it does.

The torque on the crank shaft bolt sandwiches the crank pulley onto the oil pump drive sprocket.

Make sure that you re-torque the crank bolt to specification, or the oil pump sprocket will not be driven properly, leading to low/no oil pressure.

[92Q45guy]

You really should test compression with a warm engine. To get the real results. That motor is dirty. I would run a high detergent motor oil in there for 250 miles, drain. Then put on a new filter with full synthetic oil. You might want to do it a couple of times.

[elwesso]

I agree... Since the motor is on a stand, id take the pan off (good plan to anyway), and check the mains.... Id definitely replace the mains before you start scoring the crank, IMO...

[qship96]

lets get real here,you need to find a cleaner,low mile ,much better maintained engine if you are going to spend the time and resources to be installing one.

[92Q45guy]

lets get real here,you need to find a cleaner,low mile ,much better maintained engine if you are going to spend the time and resources to be installing one.

I agree also, For the amount of time involved. I would try to find something else. And adding the oil to boost up the compression tells me that the rings are in poor condition. There should only be a 14 PSI difference MAX between all cylinders. And thats pushing it.

[gs14racer]

well i have 5 or 6 spares so i guess the plan is to drop this one for the mean time, see which one of the spares are in the best shape and do a rebuild on one of those.

[92Q45guy]

well i have 5 or 6 spares so i guess the plan is to drop this one for the mean time, see which one of the spares are in the best shape and do a rebuild on one of those.

Good choice. You might as well do it right the first time. A decent engine compression would be 180-182-185 etc. I'm pretty sure 185 is the max. When I opened up my front cover to do my chain guides the inside of my engine was like gold. Good sign the owner before me took good care of it. If I was to take all of that time I would want a 50,000-90,000 mile engine.