98 Blazer Zr2 Engine Replacement
 

Hello Everyone,
I have started to replace my 4.3L Vortec engine for my 1998 ZR2 (Vin “W”). I purchased a remanufactured (I’ll call it new since it is new to me (plus it takes less letters)) engine and have pulled my old engine. Tonight I began pulling off parts to put on the new engine. I’d really appreciate your input as I go along, and as time allows me to work on it. As you can see from the markings on the old engine in the pics below, the PO appears to have put in a non-original engine. As I have been working on this truck there has been several things that were done pretty shoddy and I have concerns and questions about a few things. So as not to draw this first posting out, I’ll start with just my first concern. By the way, I want to get the truck “back to basics” as they say (stock configuration) for a couple of reasons. First because this is for my wife as a daily driver and second because if I do want to do any type of mods or improvements in the future I’d rather start with a clean slate.



In the pic where I have the exhaust manifolds you will notice that these are the manifolds for an A.I.R. pump. I’m not sure if the manifolds are original to the truck or not. As you can see they have been capped off. Does anyone know if the ’98 Zr2’s came with the pump? I either want to mount a pump on the new engine or replace the manifolds with ones not designed for the A.I.R. pump. I am looking to put everything back to original so the PCM and the engine are in harmony (for lack of a better word). I will have more postings in this thread of things that do not look correct to me, either obvious or not so obvious and also things I am stuck on. Thanks for all your help!

Dont screw up like I did adjust and tighten down the rocker arms while the engine on the stand.As for pump That year of engine didnt have one,theres a metal tube that screws from the exaust to the intake.

Thanks. I didn't think so either, but when I go on part manufactures websites and search for the pump...there it is. Has me second guessing myself.

Just curious, why is tightening the rocker arms on the engine stand a problem? I won't be re-torquing until after the initial start-up process when the engine is back in...but curious what happened in your case?

Thanks again.

The front acessory brackets are in the way and you will have to remove those to either remove your valve covers or install them.I was thinking the old school way of how we could adjust our rockers when the engine was running even though it made a mess.Nothiing about these engines are old school.

there should be a secondary air injection pump located under the radiator on the passenger side... you are missing the tubes and check valves on the manifolds. if you don't have emission check where you live you can just keep them blocked off and run without it. it will set the check engine light without it (unless you get a tune and have it removed)

The fitting on the left manifold is for the connection up to the intake and since your right hand side manifold has a fitting with hose it does probaly go to a pump.Your is slightly different than mine sorry for the incorrect info.

Thanks. I don't remember noticing anything under the radiator that looks like something is missing. I'm going to try and get out there tonight to do some work (thank god for kerosene torpedo heaters). I'll take a look. I also didn't notice anything that looked blocked off on the intake. I think the engine came out of an S-10 and was pieced together at a scrap yard. That's why I don't even know if the manifolds are original to the Blazer, or to the engine.

the air injection pump should look like this https://blazerforum.com/forum/attach...ine=1359166560

Thanks much cool. That should be helpful.

Reluctor Ring
 

New question...I'm having a difficult time removing the reluctor ring from the old engine crankshaft (reman does not come with one). With as touchy as I have learned on here the CKP sensor and related parts are...can I use a gear puller to remove the ring? Or is that a big no-no?

On another engine I have torn apart..I am sure I probably used a gear puller...but now I am not sure if that is ok to do?

EDIT: Disregard...I used the gear puller and it popped off easy.

OK...so here's one that has me scratching my head....now remember the, engine isn't original to the truck.

So as I was pulling out the engine earlier this week, I noticed a red wire that was obviously spliced into the wiring harness and not original to the truck. It went to a engine coolant temp low on the block driver's side. Didn't think much of it but thought it was strange. Tonight I'm pulling parts off the old engine and I pulled the ECT sensor on the drivers side head. Once again didn't think much about it, but wondered why there were two. I look in the TSM, and it doesn't show a ECT in the block (unless I missed something).

Wait it gets better...I had noticed when I did my clutch last month that there was a sensor on the back of the block with nothing plugged into it. Engine ran great so realizing it was not the original motor, once again didn't think much of it. Tonight I notice it is the "Knock Sensor". I look on the new engine, and sure enough there is an empty hole where I need to put the knock sensor. I looked very carefully at the engine harness and there is no plug, no wire, or anything left over that isn't already accounted for.

Let me put one more piece into this. The PCM has a sticker on it that lists a re-flash date last year.

Here are my questions.

1. Anyone have any idea why someone would put a second ECT in the block? There is no after market gauges in the truck.

2. Is it possible that for whatever reason the PO took the wire that was designed for the knock sensor, changed it to be the second ECT plug and they flashed the PCM to change the sensor wire purpose? I don't have any idea what I'm talking about when it comes to the PCM. I don't know what can, or can't be done.

3. Since I got this truck for cheap off a lot...does anyone have the location of the PO of my Blazer so I can poke him in the eye? :)

HELP!

1: no idea, usually the blazer has 2 temp sensors, one on the head on drivers side(for the temp gauge), and one near the thermostat (for pcm)

2: not sure if it's possible, but maybe the one by the thermostat was faulty and they didn't bother to replace it... or the year of engine had a different location for it... the knock sensor has a completely different plug... the engine might have been a different year and the knock sensor may have been in the side of the block instead of the back... pictures are worth a thousand words.

3: hire a PI.

I used a gear puller on mine it came off easily.Usualy the older 4.3`s has the knock sensor on the side of the block.I beleived they changed that from 96 on up to where it was inside the timing chain cover.Some have a cap that plugs it off which is probaly to compensate for the engines that have it on the block but use the newer style timing chain cover.
Also your 98 shouldnt be any different than my 96 they should be a direct swap.Im thinkingthat the right hand side exaust manifold is from a different year engine.

1. Well it looks like what I thought was a second ECT sensor is actually the knock sensor. When I removed it, coolant came out so I assumed it was an ECT.

2. I found on the thermostat housing where a second ECT would go. But there is no sensor. Just a plug (meaning a regular "plug the hole plug". However, the service manual does list a sensor there but then in parenthesis states "If equipped". Apparently, and please correct me if I am wrong, the gauge and the pcm must share the ECT sensor located on the driver's side head.

3. All that being said, what is the sensor noted in the picture? I have nothing unaccounted for from the wiring harness. The strange thing is, the TSM detailed engine blow show that same exact location and shows a plug (plug the hole) labeled as a "Oil Gallery Plug". But inside the hole is just drilled and threaded. There is no oil galleries coming into it or little holes or anything. It's a nice shiny dry hole. That's along with a picture I misread in the manual is what made me think it was knock sensor. Any idea what it is?

that's a knock senso for an 03+ blazer... if you want to go to stock you will need to drill and tap that hole for the larger knock sensor.

Drat...no wonder the engine ran so nicely...it's not near as old as the truck...if it wasn't for the thrust bearing I wouldn't even be replacing it.

I guess I'll just keep the knock sensor where they had it on the side of the block (see pic)...that's okay....yes? New engine has a 3-year warranty so I can't do any drilling.

Stay with me Cool & Jimmy (and anyone else that is very welcome to weigh in). I can't tell you how helpful this forum is. Even if it is being just a second set of eyes to double check my work. I am sure I will have more questions coming. Anything that doesn't look right to me

Well good news for me Cool...the block has the correct sized hole and thread for the stock knock-sensor of my vehicle.

New question: While the engine and the battery is out, I have a badly rusted section just forward of the passenger side rear wheel well. I already found the formed piece at LMC Truck I can weld in. My concern is the PCM. Though I will put the grounding clamp within about 12" of the new panel to be welded in, do I need to be concerned that I could harm the PCM (or any sensors, etc)? The current would not even be heading that direction, and will be very low amperage. Like I have stated before, I am computer stupid when it comes to vehicle computers. Anyone?

if you're that concerned you could always just remove the pcm while you're using the welder.. but just disconnecting the battery should be ok... which part is bad? the actual well where it meets the cab or just the metal wheel well insert that the pcm/coolant bottle is attached to?

you're lucky about the knock sensor, I had to drill and tap mine to fit the old knock sensor (03 motor in 00 truck)

It's the body in the rocker area just in front of the REAR wheel well.

ah.. missed that part

Just a piece of information I learned tonight from GM. One of the parts guy and I are starting to become real chums :). Anyway, back in the beginning posts I had raised a question concerning whether or not my '98 ZR2 came with the A.I.R. setup or not since the manifolds on the old replaced engine were set up for that (they are capped off though). Looked up using my VIN# and discovered my truck did not come with that setup. Overall, '98 VIN "W" RPO "L35" does not have it (good news for me). However '98 VIN "Z" RPO code "K18" does have the A.I.R. setup.

Huh.. did not know that...guess you learn something new everyday....

Here's something that has me really bent out of shape. I don't know what I did wrong. Though the intakes are still off, I wanted to prime the engine with oil just so I could see that I had oil coming out of every where. I put 5 quarts into the engine and put the filter directly on to the engine oil filter mount since I have the engine on a stand. In other words its not mounted to the adapter which feeds oil thru the oil cooler, etc. Figured 5 quarts of oil should be more than enough. I used an oil prime tool designed specifically for GM V-6,8s.

That's the setup. I hooked up the drill motor to the priming tool and began turning the oil pump. From the diagram in the service manual it appeared I needed the drill motor turning clockwise like screwing in a screw. Everything was turning smoothly (by the way, it's a brand new oil pump) and oil started pumping. Another note, before I put the fuel oil pressure switch in, I did some turning until the oil came to the top of that hole. Then I mounted the sensor. Some oil was coming up through the distributor hole but overall the lifter valley was not filling with oil at all. The pump was definitely pumping oil (meaning it wasn't running dry), it felt very firm once it started, but really no oil was getting into the valley.

All of the sudden it felt like oil pump started "rubbing". A staccato type of rub, almost to the point of a grind. Like the gears inside were rubbing on the casing or something. Took the tool out and the only thing I noticed is the shaft seemed to be more wobbly then I reckoned it should. I can't remember when I connected the shaft extension to the pump shaft using a brand new plastic connector how wobbly it was. I know there was some play, but I didn't take too much notice to how much. So if the wobble is too much, I don't know if it is because maybe that plastic connector broke or if something down in the pump broke. The pump is so basic I don't know what could have broke to make it wobble like that (if it is too much).

Please help with these questions. Why wasn't any oil being pumped into the lifter valley? Why did the oil pump start rubbing/grinding? Finally, what in the hell did I do wrong??

Oil is draining now so I can pull the oil pan off and remove the pump...but what the heck happened? I am putting everything back together by the book and taking it very slow and being very anal from torque setting to the type, amount and placement of sealers.

Well got the oil pump off and apart....(what a waste of good oil). There was a little bit of the itty-bitty furry metal shavings on the drain plug magnet. Screened the rest of the oil and there was nothing.

Oil pump looks fine. Gears look great with the exception of the shaft gear has a little bit of shine at the very corner (about 1/8") of the teeth (where the teeth rest against the cover plate). But no gouging, just barely a hint of a swirl. Probably where the furry shavings came from. But besides that, there is nothing wrong with the pump I can see. The plastic shaft connecter is not broken or cracked. There is quite a bit of play where the two shafts come together (the wobble), but it seems normal.

This is the first time I have tried to prime the engine using a prime tool. I know it's got to be me, but that rub/grind just doesn't sound right. It's probably something I am being a complete idiot about. Before I put the pump back in and dump new oil in again. What am I missing? Why won't the lifter valley get oil so I can see it come out of the pushrods? What am I doing wrong? Could it be something else besides the pump and I am mistakenly connect the sound with it? I don't see how that could be, but I'm really stuck on this.

Is the oil pressure sending unit installed? If not, pressure will not build sufficiently. It will be "thar she blows" moment and lubricate the garage ceiling! Not certain, but, the balance shaft might get oil from the same passage. When priming, or running, very little oil will be in the valley. You might see a little ooze out from around the lifters, and there will be some splash from the cam lobes and balance shaft bearings, but that's about it. Pressurized oil first goes through the center of the crankshaft, then up through a passage to the lifter bores & camshaft bearings. When the lifters get pressurized, oil is sent through each push rod up to the rocker arms. From there, it drains back to the crankcase through the drain holes in the heads. The timing chain & gears rely on splash only. Not sure if this will help in locating the noise, but there ya go ;) Kinda hard to diagnose noises without actually being there.

Yeah I had a little dribble from the oil sending unit hole...but I was watching for it because I wanted to see if it would come up. Put the sending unit in and that's when I started running the drill motor steady. So are you saying that I can't pressurize the lifters with the prime tool and the lifters will not get pressurized until the engine is running? That would satisfy my concern as to why I am not seeing anything out of the pushrods/rockers.

No, the lifters should pressurize during the prime and you should see oil dribble at each rocker arm. The only thing that might make a difference, is the crank and cam are not turning and they may be blocking an oil passage in the position they're in. Have an assistant turn the crank, clockwise, while you're priming the pump. See what happens.

I bet you that's what I'm missing! I'm in for the night but I'm going to try and get some time tomorrow to put everything back together and turn the crank while priming. Let me ask you this, with the exception of the oil pump, could I have damaged anything (seals, bearings, whatever) by forcing the oil prime with the drill motor while the crank and cam were probably blocking passages?

Nope. Not even the pump. You can't hurt the bearings because nothing was turning, (cam, crank, balance shaft). The cam needs to turn to allow the lifters to pump up and bleed down on their own. If you've ever started an engine after an overhaul, without priming, the lifters go nuts hammering away until they pump up. This is why you do the prime, to make sure everything is oiled before starting.

Edit: Keep rolling the crank over while priming until every rocker arm gets oil. Don't have to go fast, just keep it moving.

Thanks Captain. I have no doubt you nailed the one simple thing that I was being an idiot about. Like I stated, this is the first time I've used a prime tool. I know what you're talking about with the lifters hammering like crazy. I hate that sound. It's like fingernails on a chalkboard :) Thanks again! I'll let you know what turns out when I get back in the garage.

Yup, makes me cringe every time I hear it ;) And you can avoid it so easily. Keep us posted.

Here's a question concerning installing the LIM. Since the LIM is so touchy and prone to leaks, I need to know if there is any reason I should not do what I am planning:

I have the GM TSM called for engine lift brackets (J41427) I use to remove my Blazer engines. As you may know, these bolt into the same holes as 4 of the LIM bolts. It strikes me as logical that once I properly torque (in sequence) the LIM bolts, the least amount of bolt removal, the better.

So, when I install the LIM, instead of using the actual manifold bolts where the lift brackets are to be installed, I'll instead immediately mount the lift brackets using their bolts as if they are the manifold bolts (torquing to spec and sequence). Then once I have installed the engine I'll install the actual manifold bolts immediately after I remove the lift brackets.

My logic being it will be one less time that bolts are removed and installed. As opposed to installing the actual bolts, then removing them to install the lift bracket bolts, then removing them to re-install the actual bolts.

Any reason this is a bad idea?

Sounds like a good plan to me :) When you tighten the bolts with the brackets installed, don't exceed the final pass torque spec, (132 inch pounds) for the LIM bolts. Check out the "Notice" in the image below:

Attachment 31854

Lower intake question. As a reminder, replading engine due to bad thrust bearing, everything else mechanical about the engine was good to go. While cleaning the surface of the LIM, I found some "imperfections". See pics (I am referring to the imperfections around the big rust colored square, not the square itself). It is a given that replacing the LIM is the ultimate way to go. However, being the imperfections seem to be within the rubber part of the Fel-Pro gasket, I wanted to ask about a couple of other options. Can I 1) use some JB Weld Aluminum filler to fill the imperfections, 2) fill them with some sealant, or 3) leave it alone? Or does what you see require a new LIM in your opinion. Obviously cost of having to buy a LIM is why I am asking this question. Thanks!

Looks borderline to me. I've read articles that specifically mention "don't use RTV". However, I'd be tempted to try the JB weld aluminum and mill it down smooth without damaging the manifold. There's a difference between "being tempted", and actually recommending it though ;) Worst case scenario, it'll leak coolant.

Back to work
 

It's been a couple months since I last posted. Fact is I haven't touched my Blazer since April due to some unexpected back surgery. Plan on picking up where i left off within the next couple of weeks. Which is cleaning the engine compartment in preparation to drop in the engine.

I have a question that regardless which way the answer goes will probably be a dumb question. Feel free to respond with the preface of “Dear Dum-Dum…” :) Within the last few weeks I have finally gotten back on what has become a project as opposed to a repair/replace. Can’t help it…every time I move on to the next part I end up breaking out the “toothbrush”. Right now I have been somewhat detailing the engine compartment, frame, doing body work (brand new to bodywork, so I’m very slow),etc.

Anyway, I finished bolting everything back onto the replacement engine back last March or so. I finished that with oil priming the engine as you saw in the previous post. Since then, the engine has been on the stand as shown in the pic with the oil still in the pan as I left it. My question is: When I finally install the engine in the truck and reconnect the oil cooler lines (which were also removed and cleaned) is it necessary for me to oil prime the engine again using the priming tool?

Since I did the prime in March, it strikes me that it is no different than if the engine was still in truck and it just hadn't been started in the last year. On the other hands, as you can see in the pic, I have the filter directly connected to the engine and once I install it…and install the oil filter adapter lines…does the fact there is no oil in those lines make a difference that requires another prime?

To be on the safe side, Just before you start it, prime it. Line up the rotor with the "6" and the dampener marks on the timing marks at the same time. Then remove the distributor. While you've got the drill in there priming, manually rotate the crankshaft slowly clockwise exactly two revolutions until the dampener marks line up again. Then drop the distributor back in so the rotor points to the "6". Priming will also fill the oil lines and the oil filter. I wouldn't take a chance on all that work you've done. Sure looks pretty!


When rotating the crank, 2 revs is good. If you go more, make sure you turn it an even number of times. If you don't, the distributor will be out of phase and the engine probably won't start.

Geez, I would not want to put that engine in the truck, I would want to display it in the middle of my living room.

I agree!