Rebuild head?

[Sullbren17]

My oil burns really bad. It could be something like piston rings or something, on my freinds mustang his oil problem was the valve guide seals? So I want to replace my valves and seals maybe if I wanted save money for new cams but what all would you need for a complete overhaul on your head?
420a motor

 

[1995silvergst]

You need to start with a compression test and a leak down test, these will eliminate some possibilities for you.

 

[BogusSVO]

First thing to do is get the head apart and see what is needed.

Seals are simple enough to do, but if the guides are wore out and need replaced, that is not something a typical DIY can do at home on the back yard picnic table.

 

[Kruger]

Yup. Do a leak down and Compression test.

Sometimes just taking off the valve cover can show you some potential problems. ( check to see if all the tiny springs around each valve seal are still tight to the seal. Sometimes the seals spring lets go and you are left with a loose fitting spring around the seal. It will be visually different from any of the sealed ones. This is only visual though. You may notice that a seal is just pooched.

still do the leakdown and comp test.

 

[Sullbren17]

How do I do a compression test?

 

[Kruger]

A compression test will only show you how much compression the cylinders are able to produce.
You need a compression tester hah. It will thread into the spark plug hole. It has a hose that goes to a gauge. an Ideal reading would be around 160psi across all 4 cylinders. Make sure you pull out your MPI fuse before you do a compression test, Or else all the cylinders that still have their spark plugs will fire. pulling the MPI fuse will kill the fuel delivery from the injectors. Also, unplug the coil pack before you do it too.

There are other posts with much more detail and pics on this site.

Get a good shop to do a leak down for you, and compression test if you arent comfortable in doing it yourself. There are ways to build your own leak down tester if you dont want to buy one. But youll still need an air compressor.. So i would just go to a good shop if you dont have a compression tester or a leak down tester.

 

[gieri002]

If you have a harbor freight near you, I'd make that your first stop. They stock both of these testers at very reasonable prices.

 

[Sullbren17]

I'm kinda in the middle of no where

 

[lee98talon]

I say make a trip to the local store and buy a leak down tester. Then return it after usage. No money spent. As, stated earlier Harbor frieght tools should have one in stock.

 

[njclimber36]

I used to work in a machine shop a ways back. If your lucky it may be valve seals, but if its a head issue, the guides are most likely shot, especially if you burn as much oil as you make it sound in the post. Another source could be the rings, but on most NA motors its the valve guides.
The guides have to be removed with an air chisel type tool and replaced. The problem is that the bore for the valves are not always centered in the guides, and if they are, the guide bores may not be perfectly centered in the head in relation to the valve seats. Bottom line is that the seats have to be redone (a complete valve job on top of the guide replacement). Its been awhile, so I don't know what the rate is for that kind of job now a days. For your motor, its probably easier and alot cheaper to buy a rebuilt from a chain store. Good luck either way.

 

[Sullbren17]

There's a machine shop here in town but they don't have a lot of tools like they can't bore my block but could I just take my head to the machine shop and he can fix everything like lap my valves and replace my valve guides?

 

[BogusSVO]

Well you might want to find a better equipped shop to do work for you then.

Some reading for you.

http://www.dsmtuners.com/forums/newbie-forum/341218-how-change-valve-guides-4g63t-head.html

http://www.dsmtuners.com/forums/cylinder-head-short-block/420045-how-have-4g63-head-rebuilt.html

I know you have a 420a engine, the write ups are based on a 4G63, but the procedures will be about the same.

Click the link in my sig line and read. VVVVV

 

[Gearhead1_6Hyundai]

How much oil are you talking about? My 92 Elantra (4G61NA) has burned oil through the PCV since day 1. I've been an Engine builder for 12 years and you usually dont see oil running down the guides like in the V8 engines. They would have to be really worn out for that. The valve stem diameter on your head is either .236" (6mm) or .276" (7mm) I dont remember off the top of my head. The Ford and Chevy V8 engines have .341" (11/32) valves. There is a lot more room in the big guides to allow oil to pass by. I once saw a V6 engine come from the dealer for oil burning problems, it had rolled off the factory line without exhaust valve stem seals on one of the heads. It still didnt burn as much oil as you would have expected. (Was still a lot though) Hope this helps!

 

[Sullbren17]

I use to put 2 quarts in NY car every morning. PS no oil leak. NY friend that had his 66 mustang he bunt oil with new valve guide seals then he replaced them again and it doesn't burn oil anymore. And the guy before me said something about running nitro through the stock motor and he rebuild it after that but I'm stupid and still bought the car. So idk much but I bet I have burnt valves and bad valve guide seals or piston rings, or the search in my cyilnder but it could a a combination I'm pulling the motor out and I'm gonna make a video with a walk about today explaining my rods and show where the scratch is Ans everything wrong.