How to inspect an l28 engine for purchase

[User0945]

My 78 280z is currently a rolling chassis and i need basically every piece on the engine bay, a guy is selling his l28 engine + transmission, driveshaft and wire harness for $750. I don't know much about these engines and how to inspect them. He says is a N42 block with N47 head in it and it has over 150k miles pulled from a car t-boned in 1995. I wanted to see what is the price for one of these engines and what checks should i make while inspecting it. Same thing for transmission and driveshaft

Edited September 14, 2020 by User0945

[AK260]

Well chap, I don’t know about the local prices where you are and the going rate for all that kit, but if the tranny is 4 or 5 speed manual, they are going on eBay for around $400-$500. So all that lot for $750 sounds (to me at least) to be well priced.

I would suggest any engine that has sat for 25 years should as a matter of good practice be rebuilt. Even if sry stored, think about those rings being sat against the bores for all that time. Even the tiniest amount of moisture in the oil or the cylinders as a by product of the combustion cycle would have caused some pitting / seizure.

Take the valve cover off and inspect:

- the state of the cam for rust and pitting
- the rockers for rust and pitting
- the timing chain and sprocket for any major wear or damage - oh and rust ;)

If you are able to take out the spark plugs, squirt some oil into each cyl. Take off any fan and aircon belts, then see if you can turn the engine a few revolutions by getting a socket in the crank damper to make sure the valve train is moving without any obvious knocking from valves (in case of a broken or bent one).

You really won’t know the true condition of the engine until you crack the head open or do a compression and leak down test - which can be difficult to do if you don’t have the engine in a rig or have a source of compressed air for leakdown testing where the engine is.

With the N42 head and some flat top pistons (standard was dished) you “should” get in the region of 9.5:1 compression for an easy power upgrade. The internet talk will point people to P90 heads for performance but the N42 with stock 44cc chambers can produce good power without performing a big part in a Gillet commercial! All of that is off topic until you get the engine. Not knowing your plans, I am trying to say that you can extract good power without having to swap the head at a later stage.

Sometimes you just don’t know what you have until the engine is apart and tested - so often it’s a matter of how much you trust the story. Good luck and keep us posted.

[User0945]

Certainly the internal condition will be unknown until its open, i plan to rebuild it but i don't want to open it to find the block is crack in half or that i have to replace the entire head. The guy says that the Engine turns over nicely by hand, im going to assume that is what you say about rotating the valve train with a socket. I was just looking at visual checks that tell me if the engine has suffer any mayor damage, other from that inspecting the transmission and driveshaft, any tips for those?.

I dont want to tune the engine to get more power, i dont know how great of a platform they are, but for now i just want to get the car and enjoy it as it was manufactured. Down the road i plan to engine swap with a 1995 BMW M3 engine or similar, im currently reading more about that swap. How is the resale value for the l28 engines? I don't know if its even possible to resell that engine once rebuild.

[dutchzcarguy]

1 hour ago, User0945 said:

How is the resale value for the l28 engines?

The L28 is i think the most wanted z engine at the moment (of the L series), also a reliable engine.  Over here i would buy it in a flash! For that price, only a good gearbox is more expensive than that!

You plan to rebuild it..  if it was stored dry and sometimes turned and oiled.. it is very possible to NOT rebuild it.  also.. nobody can look straight through the engine or gearbox, so it's always a gamble.  Look for damage and wear, a bad cam says a lot of miles and a expensive rebuild..

[AK260]

The L28 is i think the most wanted z engine at the moment (of the L series), also a reliable engine.  Over here i would buy it in a flash! For that price, only a good gearbox is more expensive than that!

You plan to rebuild it..  if it was stored dry and sometimes turned and oiled.. it is very possible to NOT rebuild it.  also.. nobody can look straight through the engine or gearbox, so it's always a gamble.  Look for damage and wear, a bad cam says a lot of miles and a expensive rebuild..

 

 

Everything he said

 

Unless there is a visible crack with water / oil seepage marks it’s virtually impossible to know without taking it apart and testing.

[Dave WM]

I would try and do a good visual, look for obvious crack (water stains), milky oil etc, turn it over by hand, if at all possible a leak down test. I am a believer in test stands, with all the harness/ecu/spark module you should be able to make one up and get a base line reading. You can mount a starter to spin it with the trans off, just need the adapter plate to mount the starter, makes it much easier to test run.

Edited September 14, 2020 by Dave WM

[Zed Head]

7 hours ago, User0945 said:

 l28 engine + transmission, driveshaft and wire harness for $750. I don't know much about these engines and how to inspect them. He says is a N42 block with N47 head in it and it has over 150k miles pulled from a car t-boned in 1995. 

Sounds like a 77 or 78 engine.  Is it a 4 speed, 5 speed, or automatic?  Was the car a coupe or a 2+2?  The propeller shaft lengths will be different between those two.  The extras for the engine are where a lot of value could be.  ECU, AFM, alternator, ignition module, distributor, injectors, fuel rail, FPR, throttle body, BCDD, manifolds, EFI relay, etc.  See if you can get a list of the extras and their condition.  If the seller has been selling off parts piecemeal, the engine might just be bare-bones and expensive to put back together.  But if it is complete it will probably add up to a good package deal.

If the engine was running when it got hit and the guy stored it in a dry garage it wouldn't be a surprise if it cranked right up and ran after some simple work.  You don't have a location shown so hard to guess about the weather there.

 

Edited September 14, 2020 by Zed Head

[Dave WM]

good point about having everything to make is run since you are starting with an empty engine bay. do you have any of the wire harness? there are two main ones the engine has a stand alone harness that is for the ECU/fuel injection. There is a separate harness IIRC for the rest of the under hood stuff, like alternator/starter/ignition, and it may be incorporated with the lights horn etc...

If you have NO wire harness at all it could be a bit of a challenge to get everything wired up. If you are just missing the ECU harness it should be not too hard. I presume you have the needed fuel/ECU relays as well? not sure on your model but on my 75 there are under the dash driver side. The ECU harness plugs into the ECU/relays/ign switch.

Edited September 14, 2020 by Dave WM

[User0945]

7 hours ago, Zed Head said:

Sounds like a 77 or 78 engine.  Is it a 4 speed, 5 speed, or automatic?  Was the car a coupe or a 2+2?  The propeller shaft lengths will be different between those two.  The extras for the engine are where a lot of value could be.  ECU, AFM, alternator, ignition module, distributor, injectors, fuel rail, FPR, throttle body, BCDD, manifolds, EFI relay, etc.  See if you can get a list of the extras and their condition.  If the seller has been selling off parts piecemeal, the engine might just be bare-bones and expensive to put back together.  But if it is complete it will probably add up to a good package deal.

If the engine was running when it got hit and the guy stored it in a dry garage it wouldn't be a surprise if it cranked right up and ran after some simple work.  You don't have a location shown so hard to guess about the weather there.

 

Is a 5 speed and the area i live is florida, the guy tells me he has most if not all the extras for the engine but i will have to see. Thank you so much for remembering me about the extras, i could have let slide that so easily, you night have just save me a lot of trouble.

[User0945]

I got the engine, transmission, headers and pieces of the trim i needed, the guy gave me more things that he said in the ad for free. I will start reading and checking how to take things apart, i rotated the engine and it seems good and will all accessories.

[AK260]

I got the engine, transmission, headers and pieces of the trim i needed, the guy gave me more things that he said in the ad for free. I will start reading and checking how to take things apart, i rotated the engine and it seems good and will all accessories.

Well done you!

 

If it turns freely, aren’t you just a little bit tempted to just throw it in and take a chance? These are very hardy engines. And yes I know, I know - I said rebuild it!

 

BTW get an engine stand and take off the oil pan to inspect the state of the muck etc in there and look for any metallic particles.

 

Ps. We love photos!!!