Question about 1986 Isuzu I-Mark

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Engine compression runs but loosing a lot of compression through the intake

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Have a compression test done--- check tappet clearance--- check that the hydraulic tappets are not locking and holding valves open

Posted on Apr 28, 2013


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1 Answer

What is a misfire in cylinder #1

Loss of compression means either piston or valve issues. You wouldn't know without a compression test with a gauge.
Misfire could be spark plug, coil or electrical issues.

Jul 24, 2017 | Kia Cars & Trucks

1 Answer


Its possible the main problem is the short drives you do. This is not enough for the engine to reach running temp long enough to keep the smog valves etc clean. You cannot loose compression while driving so go for a long high speed drive and watch in the mirror when you hit the throttle for lots of black smoke. If not get the smog system checked / cleaned at a garage and either change your car to a smaller engined type or do longer runs once a week.

Aug 12, 2015 | Cars & Trucks

4 Answers

My 1998 rav 4 has a bad miss from number 2 cylinder have replaced to spark plugs a tested the leads ,Leads are all ok.what else could be causing this problem?

Also is your Coolant or oil level low after driving? Does your spark plug look like there is lots of white or black deposits on it? These indicate mechanical problems in the cylinder.

Mar 17, 2014 | 1998 Toyota RAV4

1 Answer

1989 mustang 5.0 running good then bad missing and really rich

tell me parts you replaced sound like low compression or intake vacuum leak.replace all vacuum hoses, do a engine vacuum test and check compression see if engine has vacuum leak at intake manifold or worn out valves.

Oct 22, 2012 | 1989 Ford Mustang

1 Answer

My 99 cherokee sport 4x4 straight 6 is misfiring 3 and4 cylinder.i changed wires,plugs cap,rotor, coil pack and still runs bad.looking for a answer please

test the compression, also look for a intake manafold leak, take a can of carb cleaner and spray around were the intake mounts to the cylinder head if the engine smouth out replace the gasket or the injector o-rings.....we do a lot of valve jobs on these engines so do a compression test if below 100 psi remove the head and replace the valves and most likly the valve seats....good luck

Jan 23, 2012 | 1999 Jeep Cherokee

1 Answer

I have a nissan 300zx and its a 24 value twin turbo and the engine shakes a lot why is it doing that

When did it start acting up? first look for loose or broken vacuum hoses very carefully this is easy to miss but very important, take a piece of heater hose and listen for hissing sound concentrate near intake manifold and trace all hoses from intake to destination looking at each hose pulling each one off and inspecting. while you're doing this look at the spark plug wires for damage also. If you have the talent and a compression tester do tests on each cylinder should be around 155+ psi. If these don't pan out you may have to take it to a shop as they can run the necessary fuel rail pressure tests etc.

Oct 14, 2010 | Nissan 300ZX Cars & Trucks

2 Answers

What's the difference between a blown head gasket and a blown intake gasket?

The head gasket goes between the block and the head, and seals the combustion process, and cooling water, and (if oil is pumped obove the heads to valve components) oil pressure.

Intake gaskets seal between the intake manifold and the head, and seal against intake vacuum, and in many cases, coolant.

A badly blown head gasket will so destroy compression in the cylinder that you can hear uneven cranking as that cylinder comes up on compression, kind of a “whir, whir, WHIR, whir, whir, WHIR, whir” with the capitalized whir being the engine spinning much faster due to no compression holding the starter back.

You will never be able to hear a problem with an intake manifold gasket until the engine actually starts to fire and/or run.

Aug 10, 2010 | 1994 Pontiac Grand Am

1 Answer

Going through a lot of coolant, oil level is high

Drain the engine oil and see if there is coolant in it. Likely there is. If coolant is in the oil there is likely a blown head gasket or intake gasket. Do not run the engine or you will damage the engine bearings. A compression test, radiator pressure test, hydrocarbon test or cylinder leak down test (or a combination of those) will generally verify where the problem is.

Mar 20, 2010 | 1997 Chevrolet Lumina

1 Answer

Head gasket was leaking on my 86 mr2 Replaced the

Check all the wiring connections that you loosened or took off when you removed the head. something is loose or disconnected ,eg., ground wires .
Make sure you have spark at spark plugs whemn cranking ,and fuel pressure.
Did you try spraying starting-fluid in the intake, see if the engine runs for a little bit.
Compression to be anything above 100 psi will firean engine ,sometimes lower too.

Nov 01, 2009 | 1986 Toyota MR2

1 Answer

1986 ram 50 canadian 4 cylinder, turns over strong, wont start

To start out with. You left out some very important information. Like: the miles on the engine, the miles on the spark plugs, electronic ignition or points, but, I will attempt to give you some pointers and areas to check.
First off, I don't believe the rusty gas tank with the hole in it has anything to do with your problem. Dieseling... I guess you have to understand the differences between a gas engine and a diesel. Basically is: a gas engine runs on spark and a diesel runs on glow plugs and compression, lots of compression. True dieseling usually is a result of having a carbon build up inside your cylinders, usually on the valves. The carbon glows when it gets hot and when the engine turns over opening the intake valves it lets in fuel.Even when you shut the engine off it still makes a few turns, causing the intake valves to open letting in fuel and if there is carbon present and it's hot you may get dieseling. You also may experience what appears to be dieseling from having your timing off. It could be from having a timing chain "jump" a link, (alot of miles on the engine) or it could be from the distributer being out of time. Both may cause loss of power and the "appearance" of dieseling. It sounds like to me that you may have a lot of miles on this vehicle and it may be loosing compression thus causing the loss of power climbing hills. Loss of compression could be caused from worn rings, bad head gasket. The block section of the engine. Or: cracked, worn, or brokrn valves, the heads of the engine. Which may explain the dieseling. Bad plugs and bad plug wires can also result in the loss of power you are experiencing while climbing hills, but you would more than likely experience the engine missing, which you did not say you were experiencing.
You may want to check with a local salvage yard for another engine if the rest of the vehicle is "worth" saving or plan on doing a compression test and more than likely...some "heavy" wrenching and rebuils you engine.
I hope this helps you. If it does please let me know and put in a post about it.

Feb 25, 2009 | 1986 Dodge Ram 50

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