{"product_id":"volvo-1094","title":"Volvo Penta Thermostat Housing to Heat Exchanger Hose 859800 | MD22 TMD22 TAMD22","description":"\u003cp\u003e\u003cstrong\u003ePart Number:\u003c\/strong\u003e 859800\u003cbr\u003e\u003cstrong\u003eBrand:\u003c\/strong\u003e Volvo Penta (OEM Genuine)\u003cbr\u003e\u003cstrong\u003eOfficial Part Name:\u003c\/strong\u003e Hose\u003cbr\u003e\u003cstrong\u003eApplication:\u003c\/strong\u003e Thermostat housing to heat exchanger cooling connection\u003cbr\u003e\u003cstrong\u003eSupersedes:\u003c\/strong\u003e 859808\u003c\/p\u003e\n\n\u003cp\u003eGenuine Volvo Penta 859800 is an OEM cooling system hose that connects the thermostat housing to the heat exchanger on selected Volvo Penta MD22, TMD22, and TAMD22 marine diesel engines. It is part of the engine's closed-circuit cooling system and is used with hose clamps 961670 in applicable assemblies. 859800 supersedes the earlier Volvo Penta hose 859808.\u003c\/p\u003e\n\n\u003cp\u003e\u003cstrong\u003eCompatible Applications\u003c\/strong\u003e\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003eVolvo Penta MD22\u003c\/li\u003e\n\u003cli\u003eVolvo Penta MD22A\u003c\/li\u003e\n\u003cli\u003eVolvo Penta MD22A-A\u003c\/li\u003e\n\u003cli\u003eVolvo Penta MD22L-A\u003c\/li\u003e\n\u003cli\u003eVolvo Penta MD22L-B\u003c\/li\u003e\n\u003cli\u003eVolvo Penta MD22P\u003c\/li\u003e\n\u003cli\u003eVolvo Penta TMD22A\u003c\/li\u003e\n\u003cli\u003eVolvo Penta TMD22-A\u003c\/li\u003e\n\u003cli\u003eVolvo Penta TMD22B\u003c\/li\u003e\n\u003cli\u003eVolvo Penta TMD22P-C\u003c\/li\u003e\n\u003cli\u003eVolvo Penta TAMD22P-B\u003c\/li\u003e\n\u003cli\u003eConfirm complete engine model and cooling system diagram before ordering — the MD22\/TMD22\/TAMD22 family used different hose routing and heat-exchanger arrangements across variants\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003cp\u003e\u003cstrong\u003eEngine Family:\u003c\/strong\u003e Volvo Penta MD22 \/ TMD22 \/ TAMD22 marine diesel\u003cbr\u003e\u003cstrong\u003eSystem:\u003c\/strong\u003e Closed-circuit engine cooling\u003cbr\u003e\u003cstrong\u003eDiagram Position:\u003c\/strong\u003e Thermostat housing outlet → heat exchanger inlet connection\u003cbr\u003e\u003cstrong\u003eUsed With:\u003c\/strong\u003e Hose clamps 961670 (confirm quantity per applicable diagram)\u003c\/p\u003e\n\n\u003cp\u003e\u003cstrong\u003eSuperseded \/ Alternate Part Numbers\u003c\/strong\u003e\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003eCurrent OEM: \u003cstrong\u003e859800\u003c\/strong\u003e\n\u003c\/li\u003e\n\u003cli\u003eSupersedes: \u003cstrong\u003e859808\u003c\/strong\u003e\n\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003cp\u003e\u003cstrong\u003eWhen to Replace\u003c\/strong\u003e\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003eCracking, surface checking, or hardening of the hose wall\u003c\/li\u003e\n\u003cli\u003eLoss of flexibility or swelling\u003c\/li\u003e\n\u003cli\u003eSoft spots or deformation under normal operating pressure\u003c\/li\u003e\n\u003cli\u003eCoolant seepage at the hose body or clamp areas\u003c\/li\u003e\n\u003cli\u003eAbrasion, chafing, or physical damage\u003c\/li\u003e\n\u003cli\u003eDeterioration discovered during thermostat or heat-exchanger service\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003cp\u003e\u003cstrong\u003eService Interval\u003c\/strong\u003e\u003cbr\u003eInspect all cooling hoses during annual engine service and whenever the cooling system is drained or opened. A hose that has hardened, softened, or shows surface cracking should be replaced regardless of whether it is actively leaking. Coolant hose failure can result in rapid coolant loss and engine overheating.\u003c\/p\u003e\n\n\u003cp\u003e\u003cstrong\u003eInstallation Notes\u003c\/strong\u003e\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003eInspect the thermostat housing connection, heat-exchanger inlet fitting, and hose clamps 961670 when replacing 859800\u003c\/li\u003e\n\u003cli\u003eEnsure the hose is fully seated on both connections before tightening clamps\u003c\/li\u003e\n\u003cli\u003eRoute the hose without kinks and away from sharp edges or hot components\u003c\/li\u003e\n\u003cli\u003eAfter installation, refill and bleed the cooling system per the applicable Volvo Penta procedure\u003c\/li\u003e\n\u003cli\u003eInspect all hose connections for leakage as the engine reaches operating temperature\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003cp\u003e\u003cstrong\u003eTechnical FAQ\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eWhat did 859800 replace?\u003c\/strong\u003e\u003cbr\u003e859800 supersedes the earlier Volvo Penta hose 859808. If you have been ordering 859808 for your MD22-family engine, 859800 is the current OEM replacement.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eCan I use a generic coolant hose instead?\u003c\/strong\u003e\u003cbr\u003eNot recommended. 859800 is a specific molded hose with a defined routing path between the thermostat housing and heat exchanger. The MD22-family cooling system uses several short hoses and tubes in close proximity — matching the OEM part ensures correct fitment, routing, and sealing on both connection points.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eHow do I confirm this is the right hose for my engine?\u003c\/strong\u003e\u003cbr\u003eCheck the engine model and serial number against the Volvo Penta cooling system parts diagram for your specific variant. The MD22\/TMD22\/TAMD22 family used different hose arrangements across production runs and model variants, so diagram confirmation is the most reliable method.\u003c\/p\u003e\n\n\u003cp\u003e\u003cstrong\u003eParts Desk Insights\u003c\/strong\u003e\u003cbr\u003eThis hose is most often needed during thermostat or heat-exchanger service on MD22-family engines — it is the connection between those two components and is frequently deteriorated by the time either is being serviced. The most common issue is customers ordering by engine model alone without checking the cooling system diagram, which can result in the wrong hose when the routing differs between variants. Worth having clamps 961670 on hand at the same time — if the hose is being replaced, the clamps should come with it. Also: if 859808 is requested, advise the customer that 859800 is the current OEM replacement.\u003c\/p\u003e\n\n\u003cp\u003e\u003cstrong\u003eRelated Parts\u003c\/strong\u003e\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003ca href=\"\/products\/8131490021412\"\u003eVolvo Penta OEM Heat Exchanger O-Ring 3580818\u003c\/a\u003e — heat exchanger sealing component\u003c\/li\u003e\n\u003cli\u003e\u003ca href=\"\/products\/8131490086948\"\u003eVolvo Penta Heat Exchanger \/ Aftercooler O-Ring 3581070 | D2 D3 Diesel\u003c\/a\u003e\u003c\/li\u003e\n\u003cli\u003e\n\u003ca href=\"\/products\/8131491954724\"\u003eVolvo Penta Thermostat Gasket 3584299 – D3 Diesel\u003c\/a\u003e — thermostat assembly sealing\u003c\/li\u003e\n\u003cli\u003e\u003ca href=\"\/products\/8131492118564\"\u003eVolvo Penta Thermostat Cooling O-Ring 3586514\u003c\/a\u003e\u003c\/li\u003e\n\u003cli\u003e\n\u003ca href=\"\/products\/8266785783844\"\u003eVolvo Penta Coolant Pump 3803516\u003c\/a\u003e — closed-circuit coolant pump, special order\u003c\/li\u003e\n\u003cli\u003e\u003ca href=\"\/products\/8131513188388\"\u003eVolvo Penta Aftercooler Gasket 859196 – AQAD40 \/ TAMD40\u003c\/a\u003e\u003c\/li\u003e\n\u003c\/ul\u003e","brand":"VOL","offers":[{"title":"Default Title","offer_id":43564050645028,"sku":"859800","price":20.7,"currency_code":"CAD","in_stock":false}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0743\/5799\/7604\/files\/bd818084-86d4-421c-8a32-160d5602d357.png?v=1788656136","url":"https:\/\/marisolmarine.com\/products\/volvo-1094","provider":"Marisol Marine Company","version":"1.0","type":"link"}