[EMH]

I'm a 17 year old with a new to me 1986 Graduate with about 76,000 miles on it that looks like it's going to be a project car. I put in new fluids, spark plugs, oil, distributor cap - the works. The car still seemed to be lacking power, so I finally got around to doing a compression test. On cold engine, cylinders 1,2, and 4 all put out around 115 psi but #3 only had around 45 psi. Ran the engine for a few minutes to double check and compression only rose to about 55 psi. Funny thing is the engine sounds completely normal. I've shown the car to two mechanic friends who didn't see or hear anything out of the ordinary(even though the car was only running on 3 cylinders) I have limited funds and little experience(especially with this fuel injection magic), but I'm looking to learn. Quite a few other problems, but I figure this one is the most pressing. Any help or advice would be appreciated.

-Eric
(I'll try to put up a few pics soon)

 

[Duke58]

Eric,
Do a search on this- a 17 year old should know how to use the search feature...

You'll want to do a compression test when the engine is at operating temperature. Squirt some oil into the cylinder if its low and repeat compression test to determine if its the valve/guide or rings.

One good investment is a technical manual. I also recommend the Alfa Romeo Owners Bible by Pat Braden. Read them both. When I didn't have money, I spent a lot of time reading. You've also discovered the internet has websites with info on these cars. Since you've got more time than money, there's a lot of things to learn about these cars you can do other than buy and swap parts.

Peace.

 

[ghnl]

If you can a buy/borrow/steal a leak down tester you can pinpoint the likely problem. It could be a leaky/burned valve, stuck valve, worn/broken piston ring, faulty head gasket (or any combination of them).

If you'd like to learn more about the Bosch L-jetronic Fuel Injection system in your Spider see the link below to a web page full of information.

 

[EMH]

Duke,
Thanks for the advice. For my second compression test, I did run the engine for a good ten minutes or so. Two questions, though: do you your tests with all the spark plugs (other than for the cylinder in question of course) in or out, and roughly how much oil (regular engine oil I'm assuming) should I add to the cylinders? I do have a workshop manual from International Auto Parts. Your Alfa Bible seemed to get mixed reviews from Amazon, but I'll still look into it.

ghnl,
Thanks to you as well, especially for the link. I've got a few "friends" who might be able to help me with the leak down tester. Checked out your website and noticed you have an MG. I've got a '76 Midget myself (seems a whole lot easier to work on). Also saw you did a rebuild of your Alfa's engine. Just curious, but how hard is the whole process (time, difficulty, whatever).

Sorry about the late reply but thanks once again to both of you.

-Eric

 

[jcslocum]

Eric,

To test compression, warm the engine up, take out all of the plugs and prop the throttle (gas pedal) wide open so the engine can get air. Install your compression guage into the the plug hole and crank the engine until the needle stops rising on the guage. Record this number. Repeat for the other 3 cylinders. To test the low one with oil, just pour a little bit of engine oil into the spark plug hole. Maybe 1/2 of a shot glass would be good. Give it a minute to flow out around the top of the piston and retest that cylinder. Record the pressure.

What the oil does in this case is it helps form a seal on the rings if they are bad. If the pressure does not really change you have a problem with the head gasket or valve. What is called the top end of the engine. The pistons and crank shaft are referred to as the bottom end, more or less.

If your pressure does not change in the low cylinder, you are going to have to pull off the head to fix whatever may be wrong. Don't bother with a leak down test unless you just want to learn about how it works and what you find. Not a real hard job but it does go slowly as there is lots of stuff to unbolt. There are quite a few threads on it and one is listed in the FAQ at the top of the page. #87 if I recall.

 

[ghnl]

...saw you did a rebuild of your Alfa's engine. Just curious, but how hard is the whole process (time, difficulty, whatever).

If you have an Alfa Shop Manual, work space & tools it is not any harder than any other engine. If you decide to just remove the head make sure you clamp down the cylinders to avoid breaking the seal at the bottom. If you are doing a full rebuild then the cylinders are removed and the bottom seal is replaced.