Servicing a 1998 GTX

[ez-bore_motorsports]

I just completed repairing a broken pump in a 98 GTX, but it still won't start. Is it possible to perform a compression test on this type of engine, as you would with a car, or is the only method of checking for internal engine damage performing a leak-down test, as referenced in the manual?

Thanks in advance for any help.

 

[stevexp2]

Yes you can do a compression test to check for broken rings/worn bore however these things rarely stop an engine from starting - they just run badly. Likewise unless you have a major leak in the crankcase it should still at least fire.

A running engine needs fuel, air, spark and compression to run - so first check the fuel and spark to make sure you have those.

 

[ez-bore_motorsports]

Performing a compression test

Thanks for your response -- I have a pretty good back ground in small engine and automotive repairs -- This jet ski belongs to one of my good friends
They purchased this used with a reman engine with less than 11 hours -- first time out the fitting on the injection pump came off -- same fitting came off a second time after repairs by a shop --Sat over the winter - None of the area shops wanted to repair this now and the oil pump is no longer available

I machined the housing and fix the fitting for a permanent repair. After reassembly tried to start - engine not getting any fuel -- plugs are dry

Before pulling the carbs off ran a compression test and there is zero compression -- That is the reason for the question. Will the engine design possibility give a low compression reading and that would explain why the Sea Doo manual showed leak test and didn't mention any info for compression test

If a compression test can be performed accurately -- then I know that there is no need to dig any further -- hind sight should have done the compression test first - except there was no battery and it looked like an easy fix for the oil line

Thanks again for your help !!

 

[LouDoo]

I would do a compression test, it's a good place to start. Compression for a new engine is 150psi, with no more than 10% difference between the cylinders, 120psi is low, the engine will run but not well. If 120psi or less means an upper end rebuild.

The compression test is pretty much like any other engine. Remove the spark plugs, ground them on the lugs at the front of the engine. Do the compression test with the throttle open. If you have 0 compression you've got a hole in the piston and you need to pull the head, to see what's going on.

Most re-man engines have at least a 1 yr. warranty, with only 11 hrs. it's probably less than 1 yr., I'll do that in a weekend.

Lou

 

[jhjesse]

I just completed repairing a broken pump in a 98 GTX, but it still won't start. Is it possible to perform a compression test on this type of engine, as you would with a car, or is the only method of checking for internal engine damage performing a leak-down test, as referenced in the manual?

Thanks in advance for any help.

Is it a GTX limited?
If so, then the compression will be 130psi to 135 psi on a new reman engine. (951 engine)
If it is not a limited, then it will be somewhere around 150psi. (787 engine)