Thinking about "rebuilding" my engine this summer

[brtnstrns]

I have a '99 and am thinking about spending some time this summer pulling the motor and cleaning/replacing/upgrading the parts and doing a sort of rebuild on it. I plan to try to keep it as low cost as possible. There's nothing severely wrong with the motor, I just feel like a tear down and tidying everything up will improve its performance since its got about 115k on the odometer. I've also never completely torn down an engine so I feel like it'll be an important learning experience. I would be doing all the work myself (and probably with my father) as I have plenty of experience working on this and other cars.

I guess I'm looking for any tips/advice/warnings about doing this and keeping it with a low budget. I know I'm probably going to get asked what my budget is but I really don't have one set because I'm going to try to keep it as low as possible. I mainly want to get the engine performing as close to as if it was a low mileage motor as possible. Depending on the amount of money I make over the course of this endeavor I might also look into upgrading some parts to get a higher HP N/A motor.

I'm doing this because I'm graduating from college and have yet to find a career so I'll have plenty of time to put some work into this project. I do have a high-paying part time job that will cover most of this (I'm hoping).

(Off-topic: if anyone knows of any opportunities for an aerospace engineering major from an accredited university, let me know )

 

[JymboSlice]

are you going to be working with a hoist or without one? The way my Dad and i have pulled the motor was by unbolting the k member, sway bar, power steering pump/hoses, the brakes, etc and supporting the k member and trans with jack stands and lifting the car up with the hoist while the motor just drops down. This is probably the easiest way.. but you need a hoist.

Pulling the engine looks really challenging and intimidating but it really isnt.. im 18 and my Dad and i did it in like 3-4 hours with breaks in between. Just take your time and keep all the bolts in plastic bags so you don't lose them.

As for the engine, not really hard to take apart/put back together. Just take your time.

 

[trinity_gt]

I wouldn't do this.

115K miles isn't that much, really, for modern, clean-running EFI engines if they've been maintained. By taking it down and mucking about doing not much of anything you risk doing more harm than good.

Have you done a compression test? A leakdown test? Is the engine consuming any oil? Is it making any noises? If the engine has decent compression it's probably performing at a level equal to or better than the day it rolled off the assembly line.

There are only a few rationale to go into the motor:

• You want to upgrade to forged internals to go with a power-adder
• You need to address "hard" damage such as a spun-bearing or broken piston or ring
• You need to address "wear" like bad valve stem seals or guides or excessive bore wear etc

The diagnostics listed above will generally indicate whether the engine needs such intervention. If the engine isn't showing any signs of wear or noise or internal damage, going into it won't do much since there's nothing to fix.

Leave it be.

 

[brtnstrns]

Have you done a compression test? A leakdown test? Is the engine consuming any oil? Is it making any noises? If the engine has decent compression it's probably performing at a level equal to or better than the day it rolled off the assembly line.

Could you explain to me how to do or where to get these tests done? I can't say I've had any experience with doing such tests.

 

[trinity_gt]

Could you explain to me how to do or where to get these tests done? I can't say I've had any experience with doing such tests.

You can do a compression test yourself by getting a compression gauge from a local parts store:

Remove the spark plugs, install the tester into each cylinder, hold the throttle wide-open and crank for 4 or 5 turns. Repeat for each cylinder and look at both the absolute and relative (i.e. compare highest and lowest on the engine).

This will show basic engine health. A leakdown test will provide more detail on the state of things like the rings, cylinder walls, valves and seats etc. You need a tester:

and a source of compressed air for this one. The cylinder is pressurized and the rate at which the pressure bleeds down -- past things like the rings and valve seats -- will further define for you the condition of the engine. With the cylinder pressurized you can detect leakage paths: open the oil cap...if you hear air rushing out you can determine the rings are leaking. Out the exhaust or intake suggests valve sealing problems. And so on.

Is the engine using oil or making noise? Is it down on power? Aside from the number on the odometer do you have any reason to suspect something is wrong with it?

 

[brtnstrns]

Thanks for the info Trinity. I'll probably look into that and may have more questions for you in the future about the testing.

It isn't using oil (it is leaking oil but I'm pretty sure I've figured out where from). I'm not sure if it is truly low on power, but it currently has some problem accelerating properly between 1000-2000 RPMs (it kind of rocks back and forth as its moving forward - a mild feeling similar to what it feels like when you don't clutch properly). I thought it might be the clutch but in another thread I made people had suggested looking at the fuel/air system. I'm not entirely sure how to check all the components of the fuel and air system so if you have any tips it'd be appreciated. I did do a vacuum test with all the lines that I could see a couple of months ago and they seem to all be fine. Also, the stuttering feeling the car does between 1000 and 2000 RPMs seems to be intermittent.

As for your original question, I do not believe anything is wrong with it besides what I described above and that I get (in my opinion) much worse gas mileage than I should be (based on the numbers I've seen reading through this forum). I just figured a tidying up of everything would bring the engine to a reliable and efficient state and help it last longer (and also be a good learning experience).

 

[trinity_gt]

It isn't using oil (it is leaking oil but I'm pretty sure I've figured out where from). I'm not sure if it is truly low on power, but it currently has some problem accelerating properly between 1000-2000 RPMs (it kind of rocks back and forth as its moving forward - a mild feeling similar to what it feels like when you don't clutch properly). I thought it might be the clutch but in another thread I made people had suggested looking at the fuel/air system. I'm not entirely sure how to check all the components of the fuel and air system so if you have any tips it'd be appreciated. I did do a vacuum test with all the lines that I could see a couple of months ago and they seem to all be fine. Also, the stuttering feeling the car does between 1000 and 2000 RPMs seems to be intermittent.

As for your original question, I do not believe anything is wrong with it besides what I described above and that I get (in my opinion) much worse gas mileage than I should be (based on the numbers I've seen reading through this forum). I just figured a tidying up of everything would bring the engine to a reliable and efficient state and help it last longer (and also be a good learning experience).

The fuel economy and the intermittent stutter/hesitation might be related. Is the car showing a MIL (malfunction indicator light) on the dash?

Typical things to check include:

• O2 sensor(s) (can go "lazy" and directly affect performance and fuel economy; should be considered normal wear items and replaced every 30-60,000 miles)
• worn plugs (gaps can open up as the miles pile on leading to misfires under load; loss of sharp edges on plugs as they wear can also increase the firing voltage requirements)
• dirty MAF sensor (esp. common with "oiled" aftermarket airfilters as oil coats sensing elements; over time, normal grime can build up too; check for MAF cleaner spray at local parts store)
• dirty EGR valve (if it sticks open a bit you can get uncommanded EGR flow which can lead to rough idling and vacuum-leak-like symptoms)

You might want to get a scan tool on it and check for codes. If you know what to look for you can also check things like short- and long-term fuel trims to help judge O2 sensor health, MAF and TPS readings and so on...

 

[bhuff30]

You might want to replace the plugs. It is sometimes surprising how much smoother an engine can run with fresh plugs.

I will say as others have: don't pull apart the engine unless you have a really good reason. If you are going to open the engine up, plan on replacing all the bearings, rings and seals (basically a full rebuild). You will be surprised how quickly the costs add up, but I would consider it mandatory if you are going to completely take it apart.

 

[brtnstrns]

The fuel economy and the intermittent stutter/hesitation might be related. Is the car showing a MIL (malfunction indicator light) on the dash?

Typical things to check include:

• O2 sensor(s) (can go "lazy" and directly affect performance and fuel economy; should be considered normal wear items and replaced every 30-60,000 miles)
• worn plugs (gaps can open up as the miles pile on leading to misfires under load; loss of sharp edges on plugs as they wear can also increase the firing voltage requirements)
• dirty MAF sensor (esp. common with "oiled" aftermarket airfilters as oil coats sensing elements; over time, normal grime can build up too; check for MAF cleaner spray at local parts store)
• dirty EGR valve (if it sticks open a bit you can get uncommanded EGR flow which can lead to rough idling and vacuum-leak-like symptoms)

You might want to get a scan tool on it and check for codes. If you know what to look for you can also check things like short- and long-term fuel trims to help judge O2 sensor health, MAF and TPS readings and so on...

Actually a couple months ago when I was checking for a vacuum leak, I did everything you listed above...cleaned the MAF, checked to make sure the EGR was working properly, replaced all the spark plugs, and replaced the driver side hot O2 sensor cause it was throwing a code. I did all this because the car was performing poorly, mainly while idling. After all that and a few other things (fuel filter, retightening of some lines, etc) the O2 sensor was the reason for all the problems I was having. Now it idles fine, its just the intermittent poor performance while under acceleration. Any more ideas?

 

[screamin gt]

Any more ideas?

keep driving it for a while. take some long trips. check for codes again in case theres something pending. You won't get a CEL if the code is only pending.