1998 6.5TD G3500 Chev van coolant leak

[Roy Malone]

Engine has 281,000 miles. Collant disappears at about one gallon per hour. No visible external leaks. Pressure test shows drop when engine is running. Oil on dip stick looks good. Underside of oil filler cap is milky and some vapor can be seen coming out of small brass fitting in middle of filler cap. No loss of engine power apparent. Exhaust is clear on startup and when running(except at heavy load). Water temp 180-185 when running. Suspect intake gasket leak to intake passage or head gasket leak near exhaust valve. Any suggestions or solutions? Compression test next?

[moondoggie]

Good Day!

While the good doctor knows all, he drives a 1984 6.2L truck. You might get more responses on the 6.5L Turbo Diesel forum. This type of issue has come up many times on that forum.

My guess? I'm glad I don't own your truck right now. I'd ask the folks that frequent the 6.5L forum before losing hope, however.

Blessings!

Brian Johnson, #5044

'82 6.2 1500 4X4 1/2T pickup, 4spd man w/ OD, bone stock, 335K+, "In Rust We Trust"
'89 6.2 4X4 1/2T pickup, bone stock, 145K+
'95 6.5TD 2500 4X4 heavy 3/4T pickup, Gear Vendors Aux. OD, 183K +
'95 6.5TD 1500 4X4 3/4T Suburban, Kennedy exhaust, 203K +

[Turbine Doc]

Roy,
What year model truck do you have, sounds like symptoms of late model 97+ 6.5TD block cracking go over to the 6.5 forum & ask the question, or you might want to give Kennedy a call or email

[Turbine Doc]

Never mind if I had read I would have seen the heading it is a 98, from what I have been told the cracked block is a problem with that vintage engine to the point that GM covers it under 100K mi warranty, check with the 6.5 forum for troubleshooting to comfirm cracked block or not.

[LanceW]

Troubleshooting chart is actually in the "members" area, FYI. If the rest of the van is in good shape, a new/reman long block is not out of the question. We dropped a 6.5L into our 94 last year, and are very happy with it. Beats the heck out of buying a new vehicle. With 281,000 miles, I guess it depends on how you've used it.

[Frank V]

Behind the water pump is the timing gear cover. It has two passage ways for coolant pass to the engine block and four liquid gasket seals that could fail. It did on mine between the block and the gear cover. It was difficult to find as the coolant would leak down the front of the block, then travel along the oil pan then drip to the floor. A pain to get to and time consuming but the liquid seal was cheap.

[Roy Malone]

Thanks to all for your replies. Water finally showed up in the oil. One cylinder on the drivers side now shows 45lbs lower compression than the others. Plan to check for head gasket leak on that side. Will advise.

[Roy Malone]

Replaced head gasket on left head that had 45lb lower compression. Water leak still persists. Found 0 ring in head water passage about the size of a quarter(pvc grommet size). Looking for source. Any ideas welcome. Roy